Bisbee daily review., 1907-05-22

Low Pressure and Law ef Nature
 Called the DeSeetins Force of the
 Earth's Rotation.
 It is a matter of common obScrya- fion that when the window of warm room is opened on still winter night the cold air from without rushes into the room. Nearer the ceiling tis warmer air Is forced out of the win dow, thus completing a general atmoS- pheric circulation on miniature scale. These currents of air. which might properly be called wind. would net occur if the air within doors was uof warmer and consequently lighter than the air without.
 The range in temperature bcsCeen the equator and tine north pole al2ount5 fin winter to considerably mose than 100 degrees F., and in summer the contrast Is also great. Moreover. in summer the continents are warmer than the oceans, but in winter tic re- verse Is true. Three examples will serve to illustrate how such contrasts affect tEe winds of the world.
 At tho equator the temperature dver. ages about So degrees throughout the year Consequently the lower air flows in from regions of high pressure on each side. forming what are known as the trades. These winds cover nearly one-half Of the earths surface and blow with much steadiness the year round
 The monsoons. or -.seasona. winds" of India and the Indian ocean are the most interesting of their class. In summer the cooler ocean air pushes in toward the land, while the warmer air over the continents rises to consid- erable height and then flows cut to sea, forming q systematic circulation between ocean and continent In win- ter the ocean is warmer than the con tinent. and the winds reverse their direction
 The Hand and sea breezes- occur with much regularity near large bodies Of water in some parts of the world. The ocean is cooler than the land dur ing the day and warmer at night. caus- ing on a small scale daily inter change of air similar to that caused by the monsoons.
 A clear knowledge of the term "air pressure" is very helpful In studying the causes Of wind. Air. like stone. presses against the ground-in other words. it has weight. amounting to no less than 2.11T pounds upon every square foot of the earth's surface at sea level-but, unlike stone. the at mosphere Is elastic to a high degree and also presses in all other directions.
 On account of this elasticity of the air, certain forces which arise from differences in temperature and the earth's rotation cause 1t to become dense or heavy In some regions and rare or light in other regions.
 It Is the effort of the atmosphere to and resume state of equal density that causes the winds to blow.
 The column of mercury in a barome ter tube is always just balancing q column of air of the same diameter. reaching from the barometer to the top of the atmosphere. If the air Is dense the mercury will of course stand high in the tube. and to express this condition we use the term high mercury will stand low in the tube. and we then use the term Tow pres sure"
 Over the United States. Canada and other parts of the world the pressure is ascertained each day at numerous stations. The barometer readings. ex- pressed in inches of mercury. are tele- graphed to Q central point and there cbarted on 6 map. The exact regions where the pressure Is high or low may then be seen at glance. It has been learned from such observations that these areas are constantly moving eastward at an average rate of about 600 miles per day.
 Technically the low pressure areas are called cyclones and the high pressure areas "anticyciones-" They are frequently 1000 or more miles in diameter. The little storms of great destructive force so often called cy- clones are really tornadoes,
 The higher the pressure in any par ticular region relative to some other region the greater will be the velocity of the wind The winds blow much faster in winter than In summer, be- cause the greater contrasts of tempera- ture cause more decided differences in | pressure.
 Observations demonstrate, however. that the wind never blows in straight 1 lines, because all bodies of air when l in motion are acted upon by law of l nature called the .'defecting force of l the earth's rotation" This force turns | all wind to the right of it's course in the northern hemisphere and to the | left in the southern.
 Thus if a wind in our hemisphere | starts north it is soon turned slowly 1 toward the northeast, or if it starts i west 1t will soon turn toward the | northwest When 1t is remembered 1 that at the equator the earth is rotat- ing at the enormous velocity of 1.035 | miles an hour. one will not wonder that | such defecting force could exist All | areas of high and low pressure. from | whatever cause. therefore become | whirilng masses of air, and a iittle 1 thought will show that they must turn | in opposite directions. In the north | eru hemisphere the loFt areas. or lows as they are designated on the |