Doldrums | Define Doldrums at Dictionary.com doldrums [dohl-druh mz, dol-, dawl-] /ˈdoʊl drəmz, ˈdɒl-, ˈdɔl-/ Spell noun, (used with a plural verb) 1. a state of inactivity or stagnation, as in business or art: August is a time of doldrums for many enterprises. 2. the doldrums. a belt of calms and light baffling winds north of the equator between the northern and southern trade winds in the Atlantic and Pacific oceans. the weather prevailing in this area. 3. a dull, listless, depressed mood; low spirits. Origin of doldrums The Summer Doldrums | Fort Myers FL Homes 0 The Summer Doldrums We have all heard this phrase “the summer doldrums” and associate it with a slow down. Here is the dictionary definition: doldrums. a state of inactivity or stagnation, as in business or art: August is a time of doldrums for many enterprises.

a belt of calms and light baffling winds north of the equator between the northern and southern trade winds in the Atlantic and Pacific oceans. Here in Southwest Florida it has deeper meaning by both definitions. In the literal sense we find that the waters on the Gulf are much calmer than normal. For us boaters it is an opportunity to get out and enjoy the Gulf of Mexico without having to worry too much about choppy waters. More importantly though, from a business perspective, it is the time of year when things are most calm. Year round residents enjoy less crowded highways and shorter lines while checking out at stores. Most importantly though, they enjoy the best deals of the year. Merchants are offering all kinds of incentives to drum up summer business. Coupons, 2 for 1’s, and incentives abound this time of year as merchants vie for the local residents who clearly have the upper hand this time of year. It should come as no surprise that the same concept exists in the Real Estate market. We are in a seasonal market and the majority of residents think seasonally. Come January the market will be flooded with new listings and higher prices and transactions in April and May will be double that of August and September.

We are all familiar with the contrarian theory and for those of us that are willing to adopt it there can be rewards. In every market there are those who for whatever reason need to sell. It only stands to reason that those who need to sell in the summer have fewer buyers and will therefore pay more attention to whatever offers they receive. Are you a contrarian? If so we want to hear from you. Brad and I stand ready to assist you in finding the dream home you have been waiting for. Give us a call at 239-963-4811. Leave a Reply Pacific Ocean | Britannica.com Pacific Ocean Pacific Ocean, body of salt water extending from the Antarctic region in the south to the Arctic in the north and lying between the continents of Asia and Australia on the west and North and South America on the east. The Pacific Ocean, with depth contours and submarine features. Encyclopædia Britannica, Inc. Of the three oceans that extend northward from the Antarctic continent, the Pacific is by far the largest, occupying about a third of the surface of the globe. Its area, excluding adjacent seas, encompasses about 63.8 million square miles (165.25 million square km).

It has double the area and more than double the water volume of the Atlantic Ocean —the next largest division of the hydrosphere—and its area more than exceeds that of the whole land surface of the globe. The Pacific Ocean stretches from the shores of Antarctica to the Bering Strait through 135° of latitude , some 9,600 miles (15,500 km). Its greatest longitudinal extent measures some 12,000 miles (19,300 km) along latitude 5° N, between the coasts of Colombia in South America and the Malay Peninsula in Asia. The mean depth of the Pacific (excluding adjacent seas) is 14,040 feet (4,280 metres), and its greatest known depth is 36,201 feet (11,034 metres)—in the Mariana Trench —also the greatest depth found in any ocean. In the Northern Hemisphere the Pacific Ocean meets the Arctic Ocean in the Bering Sea . In the Southern Hemisphere the Pacific and Atlantic mix in the relatively narrow Drake Passage between Tierra del Fuego in South America and Graham Land in Antarctica.

The separation between the Pacific and Indian oceans is less distinct, but generally it is considered to lie along the line of islands extending eastward from Sumatra , through Java to Timor , thence across the Timor Sea to Cape Londonderry in Australia. To the south of Australia the boundary extends across the Bass Strait and thence from Tasmania to Antarctica. The portion of the Pacific near Antarctica sometimes is considered to be part of the Southern Ocean . Similar Topics Atlantic Ocean Because of the pattern of major mountain systems of the globe, a relatively small proportion (one-seventh) of the total continental drainage enters the Pacific—a total drainage area of less than about three times the total area of Australia. Of the rivers that drain into the Pacific, those of China and Southeast Asia are of the greatest importance; the basins of those rivers support more than one-fourth of the world’s population. The eastern boundary of the Pacific is associated with the American cordilleran system, which stretches from Alaska in the north to Tierra del Fuego in the south.

Except for its extreme northern and southern sections, which are characterized by fjords and their numerous off-lying islands, and except for the deeply indented Gulf of California , the coastal boundary is relatively regular and the continental shelf narrow. The western, or Asiatic, coastal boundary, in contrast, is irregular. Although the mountain systems there lie roughly parallel to the coast, as they do on the eastern Pacific coastlands, the western Pacific is noted for its many marginal seas. From north to south they include the Bering Sea, the Sea of Okhotsk , the Sea of Japan (East Sea), the Yellow Sea , the East China Sea , and the South China Sea . Their eastern boundaries are formed by southward-jutting peninsulas or island arcs or both. It is of oceanographic significance that the great rivers of eastern Asia—including the Amur , the Huang He (Yellow River), the Yangtze , the Xi and Pearl (Zhu), and the Mekong —enter the Pacific indirectly by way of the marginal seas. This article treats the physical and human geography of the Pacific Ocean. For discussion of the physical and chemical oceanography and marine geology of the Pacific, see ocean .

Physiography The immense area of Polynesia includes the Hawaiian Islands, the Phoenix Islands , Samoa, Tonga, the Cook Islands , the Society Islands , Tuamotu , and the Marquesas . Geology Evidence drawn from various geophysical fields— seismology , volcanology , gravimetry, and paleomagnetism ( remanent magnetism )—points to the general validity of the theory of plate tectonics . All the major physical features in the Pacific are understood to originate in plate tectonics. The western Pacific arcs of volcanic islands and deep trenches are convergent zones where two plates are colliding, one being subducted (forced under the other). The East Pacific Rise is an active spreading centre where new crust is being created. The northeastern Pacific margin is the strike-slip zone where the American Plate and the Pacific Plate are gliding laterally past each other via the major San Andreas Fault system. In the southeastern Pacific, however, the Nazca Plate and the South American Plate are colliding to form the Andes Mountains along western South America and, a short distance offshore, the Peru-Chile Trench.

The floor of the northeastern Pacific is remarkable for its several major fracture zones , which extend east and west and which, in some instances, are identifiable over distances of thousands of miles. Coral exposed at low tide on the Great Barrier Reef, off the northeastern coast of Australia. William J. Hebert—Stone/Getty Images Of great geologic interest are the seamounts (submerged volcanoes), guyots (flat-topped seamounts), and oceanic islands of the Pacific. The numerous tropical islands of the Pacific are mainly coralline. The principal types of coral reefs — fringing , barrier , and atoll —as well as the guyots, which rise within the Pacific from the ocean floor in latitudes north and south of the tropics, are explained partially by the slow subsidence theory advanced by the English naturalist Charles Darwin during the 19th century and partially by the theory of plate tectonics. Climate The wind and pressure systems of the Pacific conform closely to the planetary system—the patterns of air pressure and the consequent wind patterns that develop in the atmosphere of the Earth as a result of its rotation ( Coriolis force ) and the inclination of its axis ( ecliptic ) toward the Sun.

They are, in essence, a three-celled latitudinal arrangement of the atmospheric circulation, with the systems in the Northern and Southern hemispheres mirroring each other on opposite sides of the Equator. The vast extent of open water in the Pacific influences wind and pressure patterns over it, and climatic conditions in the southern and eastern Pacific—where the steadiness of the trade winds and the westerlies is remarkable—are the most uniform on the globe. In the North Pacific, however, conditions are not so uniform, particularly the considerable climatic differences between the eastern and western regions in the same latitude. The rigour of the winters off the east coast of Russia , for instance, contrasts sharply with the relative mildness of winters in the region of British Columbia . The trade winds The trade winds of the Pacific represent the eastern and equatorial parts of the air circulation system; they originate in the subtropical high-pressure zones that are most pronounced over the northeast and southeast Pacific between latitudes 30° and 40° N and S, respectively.

The obliquity of the ecliptic (an angle of 23.44° that is the difference between the planes of the Earth’s rotation on its axis and its revolution around the Sun) limits the seasonal shifting of the Pacific trade-wind belts to about 5° of latitude. The easterly winds between the two subtropical zones form the intertropical airflow and tend to be strongest in the eastern Pacific. The equatorial region, where the trade winds of the Northern and Southern hemispheres converge, is an area of calms or light variable breezes and is known as the doldrums . Fog enveloping the Golden Gate Bridge, which spans the entrance to San Francisco Bay in northern … © MedioImages/Getty Images The trade winds, especially in the eastern Pacific, convey relatively cool air toward the Equator; in moving, the air comes in contact with the sea and thus becomes increasingly humid and warm, and high lapse rates (the term used to denote the rate of change of air temperature with increasing height above sea or land surface) result. The average wind speed of the Pacific trade winds is about 15 miles (24 km) per hour.

The weather in the trade-wind belts is normally fine, with relatively little cloud cover; such clouds as there are characteristically take the form of broken cumulus (small piles of clouds with flat bases) at about 2,000 feet (600 metres) above sea level. Precipitation, usually in the form of light showers, is slight. Off the west coasts of the American continents in the trade-wind belts, upwelling of cold subsurface water causes the overlying air to be cooled below its dew point (the air temperature below which water vapour condenses as dew), with the consequent widespread formation of low, thick clouds. Fog in those regions is not uncommon. Tropical storms Although in general the climatic conditions of the trade-wind belts are characteristically regular and uniform, storms of great violence do originate there. In such storms, winds of exceptionally strong force spiral inward toward a centre of exceedingly low atmospheric pressure. These storms, generically called tropical cyclones , are known in the western Pacific as typhoons ; Australians use the term cyclones for those that occur several times a year off that continent’s northeast coast and batter the Great Barrier Reef .

While the mechanism that triggers typhoons and other tropical storms is not completely understood, ideal conditions for their development occur in the western Pacific between latitudes 5° and 25° N during late summer and early autumn, when the temperature of surface waters is at least 81 °F (27 °C). The regions to the east of the Philippines and in the South and East China seas are notorious for these storms, which imperil shipping and often cause severe coastal flooding accompanied by loss of life and property. “Supertyphoon” Chaba (right) approaching Japan and Typhoon Aere (left) hitting Taiwan, … NOAA The westerlies Within the belts of the westerly winds, cold easterly winds from polar regions meet the warm westerly winds of the middle latitudes, causing the formation of the traveling depressions characteristic of middle latitudes. The zone of convergence, or polar front, is most strongly developed in winter, when the contrast in temperature and humidity of the air between the converging flows is greatest. The westerlies in the Southern Hemisphere are steady and strong, and their popular name, “brave west winds,” is apt.

The gales that accompany the depressions have given rise to the term “roaring forties,” named for the latitudinal zone in which the storm winds are of greatest frequency. The monsoon regime The western Pacific is subject to a seasonal climatic regime that replaces the planetary system. This is the regime of the monsoon (rain-bearing winds), which is associated with the heating of the Asian landmass in summer and its intense cooling in winter. The heating of air masses over tropical Asia in summer initiates a low-pressure system, which becomes the focal point of the trade winds of both hemispheres. The doldrums , therefore, do not exist in the western Pacific during northern summer because of the immense flow of maritime air into the Asian low-pressure zone. The cooling of the continent in winter results in the development of the Asian high-pressure system, which leads to a strengthening of the trade winds of the Northern Hemisphere. As a result of seasonal changes in pressure and wind circulation, marked seasonal contrast between continental and maritime influences—the first associated with drought and cold and the second with moisture and heat—is to be found in the whole of the western Pacific from the Sea of Japan southward.

Temperature and salinity Temperature The oceans tend to be stratified, the principal factor being temperature; the bottom waters of the deep parts are intensely cold, with temperatures only slightly above freezing. The surface zone, where temperature variations are perceptible, is between 330 and 1,000 feet (100 and 300 metres) thick. It is more compressed in the temperate eastern Pacific, along the coasts of North and Central America, where cold water appears at a shallower depth compared with the central and western Pacific. Ocean temperatures in the North Pacific tend to be higher than those in the South Pacific because the ratio of land to sea areas is larger in the Northern Hemisphere and because Antarctica also influences water temperature. The mean position of the thermal equator (the line on the Earth on which the highest average air temperatures are found; the line migrates latitudinally with the changing angular distance from the Equator of the Sun) in the Pacific, although it lies in the Northern Hemisphere, is nearer to the geographic equator than in the Atlantic and Indian oceans. There is a pronounced difference in temperature and salinity between the surface and deep zones of the Pacific.

The deep zone, which contains about 80 percent of the ocean’s volume, has relatively stable temperature and salinity patterns; its average temperature is 38.3 °F (3.5 °C). Salinity The salinity patterns of the surface waters of the Pacific are influenced largely by wind and by precipitation and evaporation patterns. The waters within the belt of calm and variable winds near the Equator have lower salinities than those in the trade-wind belts. In the equatorial belt, relatively large amounts of rain fall and little evaporation occurs, both because of low wind speeds and because of the generally cloudy skies; salinity in the equatorial belt runs as low as 34 parts per thousand. Latitudinal variation in precipitation and evaporation and its relationship to major wind belts and … Encyclopædia Britannica, Inc. The highest surface salinities in the open Pacific occur in the southeastern area, where they reach 37 parts per thousand; in the corresponding trade-wind belt in the North Pacific, the maximum salinity seldom reaches 36 parts per thousand.

Pacific waters near Antarctica have salinities of less than about 34 parts; the lowest salinities—less than about 32 parts—occur in the extreme northern zone of the Pacific. The heavy rainfall of the western Pacific, associated with the monsoons of the region, gives rise to relatively low salinities. Seasonal variations are significant in the western Pacific as well as in the eastern Pacific, caused by seasonal changes in surface currents . Hydrology Surface currents Pacific trade winds drive surface waters toward the west to form the North and South Equatorial currents , the axes of which coincide with latitude 15° N and the Equator, respectively. Squeezed between the equatorial currents is a well-defined countercurrent , the axis of which is always north of the Equator and which extends from the Philippines to the shores of Ecuador . The major part of the North Equatorial Current swings northward in the vicinity of the Philippines to form the warm Kuroshio (also called the Japan Current). To the east of Japan the Kuroshio swings eastward to form the Kuroshio Extension.

The branching of this current in the region of 160° E results in the movement known as the North Pacific Current . The surface waters of the Bering Sea circulate in a counterclockwise direction. The southward extension of the Kamchatka Current forms the cold Oya Current , which flows to the east of the Japanese island of Honshu to meet the warm Kuroshio waters in the vicinity of 36° N. The cold, southeast-flowing California Current forms the eastern segment of the returning branch of the North Equatorial Current system. The main part of the South Equatorial Current divides into three large branches as it flows westward. The two westernmost branches, on reaching the east coast of Australia, swing south to form the East Australian Current , which, becoming the Tasman Current, turns back to the northeast and dissipates west of New Zealand.

The easternmost branch flows first to the south, roughly along the 180° meridian, before turning back to the east in the vicinity of 50° S as the warm South Pacific Current ; between 80° and 90° W this flow turns northward and then westward as the Mentor Current, the waters eventually returning to the South Equatorial Current. Flowing between Antarctica and the South Pacific Current is the cold Antarctic Circumpolar Current , which constitutes the other portion of the South Pacific circulation system; as it reaches the South American coast in the region of 45° S, one branch flows northward along the coast to form the Peru (Humboldt) Current , and a second branch flows southward to pass through the Drake Passage. Periodically—usually at intervals of three to four years—an anomaly of ocean currents and climatology called El Niño occurs in the South Pacific. This event is associated with the appearance of unusually warm ocean conditions off the tropical coast of South America and with changes in tropical atmospheric patterns (called the Southern Oscillation) that can adversely affect fishing, agriculture, and precipitation patterns along the west coast of South America.

During particularly strong events, El Niño can cause weather anomalies in the equatorial and southern Pacific and in northeastern South America, Asia, and North America. Deepwater circulation Observations of temperature and salinity at different levels in the ocean reveal well-defined layers, each forming a water mass distinguished by its own temperature and salinity characteristics. It appears that the most important influence on the vertical circulation of the Pacific is the cold water generated around the Antarctic continent. This dense circumpolar water sinks and then spreads northward to form the bottom layer of the greater part of the Pacific. It is thought that cold, deep water flows northward in the western Pacific in a relatively well-defined current from the vicinity of Antarctica to Japan. Branches from this deep main stream convey cold water eastward and then poleward in both hemispheres. Deepwater circulation is influenced by the descent of surface water at zones of convergence of neighbouring water flows. In the Pacific Tropical Convergence, which coincides with the Equatorial Countercurrent , water sinks to a depth of about 300 feet (90 metres) before it spreads laterally. The Pacific Subtropical Convergences are located between 35° and 40° N and S.

Water that sinks at the convergences spreads laterally at increasing depths as the distance from the Equator increases. The Antarctic Convergence lies in the zone of the southern westerly winds. A corresponding Arctic Convergence is prominent in the northeastern Pacific. To compensate for downward-moving water, some water rises at zones of divergence, particularly along the so-called cold-water coasts of both North and South America, where upwelling of cold water is a well-marked phenomenon. Tides In contrast to the tides of the Atlantic—which are almost always semi diurnal (twice-daily) occurrences—those of the Pacific include many instances of diurnal (daily) and mixed tides . In the diurnal type of tidal oscillation, only a single high water and a single low water occur each tidal day (which lasts for about 24 hours and 50 minutes). Tides of this type occur in the Gulfs of Tonkin and Thailand in Southeast Asia, the Java Sea in Indonesia , and the Bismarck and Solomon seas north and east of the island of New Guinea. Mixed tides, in which both diurnal and semidiurnal oscillations appear, are characterized by large inequalities in successive high (or low) water heights.

This type of tide is prevalent along much of the Pacific coast. Mangroves (Rhizophora apiculata) at low tide on the coast of Thailand. C.B. Frith/Bruce Coleman Inc. At certain places in the South Pacific, the natural period of oscillation of the sea accentuates the solar tidal oscillation. At those locations the time of the am (or pm) high (or low) water occurs at approximately the same time for several days in succession, instead of getting later each day by about 50 minutes (as is generally the case). The tide at Tahiti , for example, follows the Sun and not the Moon—the time of high water occurring, day after day, at about midnight and noon and that of low water at about 6 am and 6 pm. In general, tidal ranges within the Pacific are small. That at Tahiti is about 1 foot (0.3 metre); at Honolulu it is about 2 feet (0.6 metre); at Yokohama it seldom exceeds 5 feet (1.5 metres); and at Cape Horn it is never more than about 6 feet (1.8 metres).

However, in the upper reaches of the Gulf of California and in Korea Bay , tidal ranges of 40 feet (12 metres) are common, while around most of Australia tides range from 6 to 33 feet (1.8 to 10 metres). Page 1 of 2 Pacific Ocean - Student Encyclopedia (Ages 11 and up) The major feature of the Pacific Ocean is its enormous size: not only is it the largest ocean in the world, it is also the world’s largest single physical feature. With an area of about 64 million square miles (166 million square kilometers), it is twice the size of the Atlantic Ocean and occupies nearly a third of the surface of the Earth-more than the area of all Earth’s land surfaces. The Pacific reaches about 9,300 miles (15,000 kilometers) from Antarctica almost to the Arctic Circle in the Bering Sea. Its greatest dimension stretches from east to west, with nearly half the length of the Equator lying across its surface-11,000 miles (18,000 kilometers).

Article Contributors The Summer Doldrums | GulfPointeProperties.com The Summer Doldrums August 21, 2014 By admin The Summer Doldrums by Dick Dohack We have all heard this phrase “the summer doldrums” and associate it with a slow down. Here is the dictionary definition: doldrums. a state of inactivity or stagnation, as in business or art: August is a time of doldrums for many enterprises. a belt of calms and light baffling winds north of the equator between the northern and southern trade winds in the Atlantic and Pacific oceans. Here in Southwest Florida it has deeper meaning by both definitions. In the literal sense we find that the waters on the Gulf are much calmer than normal. For us boaters it is an opportunity to get out and enjoy the Gulf of Mexico without having to worry too much about choppy waters. More importantly though, from a business perspective, it is the time of year when things are most calm. Year round residents enjoy less crowded highways and shorter lines while checking out at stores. Most importantly though, they enjoy the best deals of the year. Merchants are offering all kinds of incentives to drum up summer business.

Coupons, 2 for 1’s, and incentives abound this time of year as merchants vie for the local residents who clearly have the upper hand this time of year. It should come as no surprise that the same concept exists in the Real Estate market. We are in a seasonal market and the majority of residents think seasonally. Come January the market will be flooded with new listings and higher prices and transactions in April and May will be double that of August and September. We are all familiar with the contrarian theory and for those of us that are willing to adopt it there can be rewards. In every market there are those who for whatever reason need to sell. It only stands to reason that those who need to sell in the summer have fewer buyers and will therefore pay more attention to whatever offers they receive. Are you a contrarian? If so we want to hear from you. Brad and I stand ready to assist you in finding the dream home you have been waiting for. Give us a call at 239-963-4811.

Stuck in the Doldrums: An Attack Plan Stuck in the Doldrums: An Attack Plan Share Shares 10 Oh my word…did Jen Hatmaker EVER sum up my world right now. This. Is. Me. Swirling in a tornado of mediocrity and frustration with myself. Needed this today. You might just need it, too: “dol·drums [dohl-druh mz, dol-, dawl-] noun ( used with a plural verb ) 1. a state of inactivity or stagnation, as in business or art: August is a time of doldrums for many enterprises. 2. a belt of calms and light baffling winds north of the equator between the northern and southern trade winds in the Atlantic and Pacific oceans. 3. a dull, listless, depressed mood; low spirits. If you feel stuck today, can I suggest approaching the doldrums in a reasonable way, one tiny element at a time? Alone, none of these are monumental, but together they begin to lay small paver stones out of the mire, forging a path back to health.

It will be imperfect with incremental steps forward and back, but God can use your brave movement to soothe the shame of stagnation and restore peace to the chaos.” Here’s the full blog . Take 3.24 minutes and check it out. Happy Wednesday to you all from my bronchitis-infused doldrum to yours. Trans-Atlantic Weather - Franks-Weather - The Weather Window The Return Introduction to the Tropics This first section is a brief description of tropical weather where convection is the dominant factor. There are not the air mass differences and frontal systems that we see in mid latitudes. In broad terms, heating from the sun creates a low pressure trough, virtually right around the globe. Inflows to this trough from north and south, deflected by the Coriolis effect, give the NE and SE Trade Winds. This Inter Tropical Convergence Zone is an area of much cloud and rain with light variable winds - usually known as the Doldrums. Idealized View of General Circulation of the Atmosphere With the kind permission of the Editor of the MRNA Yachtsman's handbook The diagram shows schematic cross section and surface winds on the global scale.

Air going pole-wards from the sub-tropical highs meets air coming from the polar regions at the polar front. Air going equator-wards from the highs meets air of similar origins at the ITCZ. During the northern Summer the ITCZ moves north to about 14 deg N off the African coast and about 5 deg N over the Gulf of Mexico/Caribbean area. In January it is still just north of the equator, about 5 deg N off Africa but south of the equator off Brazil. Over the major continents of Africa and India, due to the greater heating of the ground compared to the oceans, the ITCZ gets further N to about 20N. The large low pressure areas over land associated with the ITCZ lead to the persistent and often strong SW winds of the monsoon, particularly over the Indian Ocean The ITCZ When the sun moves northwards in the northern hemisphere Summer, the SE Trades cross the equator and turn to become SW due to the Coriolis effect.

In general, pressure within the tropics changes only slowly from day to day, but a diurnal cycle, an" Atmospheric Tide " will be very obvious with pressure maxima at around 1000 and 2200, minima at about 0400 and 1600 - all LT. The range of pressure in this cycle is likely to be about 3-4 hPa. . Be wary of any pressure change that bucks these trends. The NE Trades are characterized by generally fine weather with small cumulus clouds, scattered showers and moderate winds, often more E than NE to the south of the high, However, within, the Trades there are troughs of low pressure, known as Easterly Waves, moving E to W at around 10-15 kn. They give areas of heavier showers, perhaps with thunder. The wind will back ahead of them to NE and veer to SE behind. There is little warning of these waves which can occur at intervals of between 2 and 6 days or so. Local heating over islands can often give showers, especially when the islands are mountainous eg Dominica which has frequent very heavy showers giving very dense forests and fast flowing rivers.

Such showers drift downwind of their source. An Easterly Wave . Areas of enhanced convection give enough upwards air movement to create an area of lower pressure. Air movement into these troughs form an "inverted" V-shape. This moves in the general east to west flow. The Coriolis Effect in Low Latitudes Most sailors will know that the strength of the wind depends upon the pressure gradient and that the Coriolis effect causes the wind to blow nearly along the isobars, but slightly across them towards low pressure. The closer the isobars, the stronger will be the wind. What some may not realize is that the relationship varies with latitude. For a given pressure gradient, the lower the latitude the stronger will be the wind for the same gradient. A pressure gradient that gives a wind of 20 kn at 50 deg N, will give winds of about 25 and 30 kn at 40 and 30 deg N respectively. However, in low latitudes the pressure gradient to wind relationship progressively breaks down as the air moves increasingly across the isobars. This is due to the weakening of the Coriolis effect.

[For the mathematically inclined, the Coriolis effect is proportional to the sine of the latitude.] Right at the equator itself, the wind blows directly across the isobars. At or very near the equator, a low pressure will quickly fill up and a high collapse. Tropical Depressions From May until December, tropical depressions must always be a possibility, although any in these two months are relatively unusual. June to November is the effective season with the peak activity in August, September and October. The trigger is often an easterly wave although it is rather more complicated than just that. If there is too much change of wind speed with height then tropical depressions are unlikely. If winds diverge near the tropopause, then this increases the upwards movement of air in the easterly wave thus increasing the inflow of air at sea level and encouraging the formation of a circulation of winds because of the Coriolis effect. Sea temperatures are fairly critical. Large areas of around the size of the USA with temperatures >27 C are needed. This is one reason why the S Atlantic has never had a hurricane. [NOTE.

In 2003, after I first wrote this page, there was a hurricane in the South Atlantic. It may be too facile to say that this was an effect of global warning, but it does imply that sea temperatures must have been higher over the South Atlantic than at any time in the past 1000 years or so for which there are accounts of ships crossing the oceans.] A further requirement is that there must be enough Coriolis effect for the winds flowing into the low pressure to form a spiral rather than just fill up the low. This means that Atlantic tropical depressions only form at about 10 deg or more north of the equator. Warnings are usually good and well in advance although they may not predict too well the most likely places to be worst affected until about 48 hours ahead. "Hurricane" is the name given to the severest form of tropical depression in the N Atlantic. Such storms in the China Sea are known as Typhoons - meteorologically, they are one and the same thing.

Terminology used in bulletins and advisories is as follows TERM Hurricane Force 12 or more Hurricanes are categorized according to their central pressure Category 1 to 5 with 5 being the deepest and most vigorous. Early in the season tropical depressions seem to form anywhere between the coast of Africa and the Gulf of Mexico. Those that form near Africa usually do so before the end of September and often to the S or SE of Cape Verde Islands near an area of very warm sea. At this time of year the ITCZ is not far south of Cape Verde. Their tracks are W or WNW across the Atlantic. Once north of about 15 N they start to curve to the right (ie N and then NE). Those tracks usually take them to the west of the Azores, near or over the Caribbean Islands. Some tracks parallel the eastern sea board of the US, some cross the coast near Florida. Very rarely a hurricane will turn to the north near or even to the east of the Azores. Later in the season, formation tends to be confined more to the Caribbean/Gulf of Mexico area.

Sometimes they just wander around rather aimlessly but, more often, tracks are N towards Texas or NE toward Florida and the more western islands, such as Cuba, the Dominican Republic and Puerto Rico, then on to the Bahamas. Those that cross the coast into mainland USA usually weaken fairly quickly as they lose contact with their major energy source - the sea. Any hurricane near the coast or over land can spawn tornadoes. Typical numbers of storms (ie tropical depressions with F 8 or more) Type of Storm <1 0.1 Over the past 200 years or so, in the months of January, February and March there have been one storm in each month. April is the only month in which there is no recorded tropical depression in the Atlantic. In the Cape Hatteras, South Texas and Florida areas the probability of any specific location being within 100 miles of a tropical storm centre is about one year in three. Near New York it is about one year in five. Over the S tip of Florida, Cuba and the Bahamas the frequency is about one year in two or three, a little less over BVI, decreasing southwards to about one in five over Grenada and one in ten over the Venezuelan coast.

Near the eastern sea board of the US mainland during the hurricane season, it is best to be as far north as possible, probably north of New York at least. Tropical storms have been known to get as far north as Nova Scotia. If in the Caribbean, then nowhere is really safe. Best advice is to be as far south as possible - perhaps Grenada in one of the deep bays on the south coast or in the Trinidad/Venezuela area. Pilot books advise against being in the Bahamas during the hurricane season. Some European insurance companies may refuse to insure yachts in the Caribbean during the hurricane season. Perhaps slightly worrying is that climate changes now occurring could result in a lengthening of the season due to sea temperatures getting a little higher. The Met Office numerical weather model is particularly good at predicting hurricane movements and has been used by the US Severe Storm Centre, Miami. For information on hurricanes and tropical storms, go to the Met Office Page or the NOAA tropical storm FAQ page . Weather to be expected en routeRoutes for Trade Winds U.S.A.

2001 Lagos to Canaries and the Cape Verde Islands The Portuguese Trades resulting from the Azores high and the Spanish heat low give the prevailing northerly winds down much of the Iberian Atlantic coast. During October/November, fairly weak frontal low pressure systems move rather erratically between SW Portugal and Madeira, generally from the NW. Winds can therefore be rather variable although the predominant winds from Lagos to Madeira are likely to be between NW and NE mostly F 4-5. Any rain is mainly on cold fronts. Gales are fairly rare ~ 5% probability. South of 25 N gales are unusual. Because of the Portuguese Trade wind current, the sea will be rather cold and the air temperature, likewise, will be on the cool side. Madeira, itself is near the northerly fringe of the NE Trades and the southern limit of the Portuguese N Trade winds. Note that wind statistics from Island stations are not representative of the open sea, eg Funchal, Madeira shows a predominant daytime S because of sea breezes and sheltering from the N. Around the Canaries there are some very marked local effects that can give winds much stronger than over the open sea.

Funnelling between Tenerife and Gran Canaria, the effects of the wind blowing slantwise onto the steep cliffs of the islands and funnelling down some valleys all may lead to winds up to 40 or 50 kn. Winter lows occasionally affect the Canaries, look out for pressure falls of about 10 hPa below normal. From the Canaries southward, the winds are very firmly NE Trades, still relatively cool until about 20N, They then become hot, dry and dusty due to the Sahara - this is the Harmattan. Visibility can be quite poor in haze. With high pressure over about 1030 hPa the Harmattan can become very strong. Approaching Cape Verde, the effects of the ITCZ may start to become evident. It should be quite well south by that time but it does meander somewhat. Easterly waves, associated with small disturbances on the ITCZ, can give very heavy showers, thunderstorms and, of course, strong gusts. A contributory factor is the very high sea temperature reaching about 29C just SE of Cape Verde. It is these troughs that may spawn hurricanes further to the west.

Gusts can be enhanced by down-draughts to the lee of high ground and by valley funnelling. Once away from Lagos, the currents should be S, increasingly SW, going driven by the prevailing winds. Cape Verde to Antigua The NE Trades near Cape Verde will become more E or ENE by about 35 W and be generally F 3-5. Chances of gales are just about zero, calms do occur with a probability of around 5-7%. Easterly waves are likely to give increased cloud, heavy showers and stronger, gusty winds from time to time. They are quite hard to detect from conventional observations although satellite pictures should show the increase in cloud. They are unlikely to be well forecast. Signs will be thickening cloud to the east, and perhaps lightning. There may not be much of a pressure fall ahead of a wave, indeed the pressure may rise just ahead of the first squall. The Caribbean Near the Leewards in December, winds will be predominately E but with a fair number of NE and SE.

Near the N and S tips of the islands, winds can increase by a force or so and become more pronounce NE or SE - whichever is the more adverse in my experience! Between the islands, the currents are also accelerated and deflected. So take care not to get taken down too much to leeward when on inter island passages, you could all too easily find it difficult to come up to wind against an adverse current. Over the Caribbean, as a whole, from about Cuba southward, winds are generally around F 4-5 and hold up at night with few calms. Winds are more variable and generally lighter during August to October due to the proximity of the ITCZ although, paradoxically, this is also the time when easterly waves and tropical storms are most likely. Otherwise, showers during December to February are relatively few except where they are formed by a combination of heating and orography. These showers can be heavy with gusts or squalls. Visibility is often good although it can be quite poor, especially when it is more windy than normal and, of course, if you are looking for a low lying island such as Barbuda.

For the rest of the year there are rather more showers, especially with Easterly waves which can occur at any time. Showers can then be particularly prolonged, heavy and frequent with very strong squalls. On the other hand, I have had a rare day in March when it was cloudy, rainy and windless for much of the day. Very rare. Further north than Cuba, especially in Winter, extra-tropical lows with their frontal troughs can give strong to gale force winds with cloud and rain rather than showers. See the notes below regarding the US coast. Eastern Seaboard of the USA The Florida Current Typical position of the Florida current. Note the extreme positions of the North or West Wall. Note, also the eddies on both sides of the stream. Solid line - Florida Current/Gulf Stream Dotted line - North Wall extreme positions An important feature is the Florida Current which becomes the Gulf Stream as it leaves the coast N of Washington DC. The N or W wall of the current can get very near the coast off Cape Hatteras and Fort Lauderdale and as near as 30 miles off near the Savannah River.

Florida to Delaware From Fort Lauderdale to the Savannah River, the climate in the far S is typically tropical maritime, much as the Caribbean but there is a steady transition to a continental type to the N of Florida. The Azores high is a dominant feature and, in the Winter, the North American Winter high also. In the Winter occasional extra tropical (mid latitude) depressions can make their presence felt as far south as the Gulf of Mexico. From the Savannah River northwards is a breeding ground for frontal depressions, particularly in the Winter months. It is then that lows forming over the Gulf of Mexico, migrate northwards. These often deepen rapidly in this area to become the infamous Cape Hatteras lows. When the wind is blowing across the N wall of the Florida current from the W or NW, there is an increase in turbulence and wind speed. This effect is very limited and will disappear a few miles towards either colder or warmer water. In the south, sea breezes can be strong and the whole stretch of coast is generally rather windy. Tropical storms are always a possibility in the season. Probability (%) of winds > F 5 Area 55 12 In the south, rainfall is likely to be convective or associated with Tropical storms.

Further N, frontal rain is common. The N wall of the Florida current is frequently cloudy with low stratus. From about Cape Hatteras northwards, sea fog is likely in the Spring/early Summer whenever warm air is crossing the Florida current/Gulf Stream (from a S or SE point). Sea Temperatures off the Eastern Seaboard of the USA Isotherms in February. Note the strong gradient off the Cape Hatteras area. The diagram shows the very strong gradient of sea temperature of the coast of the US. This is one of the factors that influences the development of depressions Delaware to Boston Mobile, frontal lows are common, especially during the Winter from November to March when lows are likely every two or three days. Winter gales, rain and sea fog are frequent. Gales occur with about 30% probability about 150 - 200 miles off shore. The Summer half of the year is quieter with fine spells and periods of low pressure, much like the UK. To the N, the effect of the Labrador current is to give a high probability of sea fog banks. Gales off the US Coast Frequency of gales, Force 8 and above off the coast of North America.

Note the very high values in the Winter. These are due to the large number of depressions forming to the southwest, particularly the Cape Hatteras Lows. The return trip The lows forming off the Eastern seaboard of the US can either move across the Atlantic or create breakaway waves that have the same effect. Either way, it can be quite disturbed between the US Coast right across the Atlantic. During 2000, for example, the Azores high collapsed and sank a long way south for several weeks in late May/June. Anyone crossing the Atlantic direct to the UK or via the Azores would have had a rough passage. The optimum time for the return trip, whether direct or via the Azores is probably to leave the US or Bermuda in sufficient time to get to the Azores before any early season hurricanes have a chance to turn northwards to the east of the Caribbean but late enough to avoid the worst of the Winter Atlantic depressions. This will mean dodging east coast depressions to get from the US to Bermuda, perhaps around mid to late May, so as to be on passage from the Azores to the UK or to Lagos during June/July.

To minimize the chance of gales, keep south of 40N for as long as possible. Remember that August is a month when very severe Atlantic depressions can occur - eg the Fastnet Storm. High sea temperatures, very moist air and copious quantities of latent heat are important here as they are in hurricane formation. Anyone wanting to return to the Caribbean after the hurricane season could have some difficult decisions with the predominantly E to ENE winds and an adverse current. Leaving from a little S of Cape Hatteras could give a reasonably free wind until near the Bahamas. Thereafter, it is likely to be a close fetch with an adverse current. In the Atlantic Pilot, Anne Hammick advises against crossing the Florida current in a vessel that cannot make 10 kn!

Question: What is the name of the calms and light baffling winds in the Atlantic, Pacific and Indian Oceans?
Answer: Doldrums