Query: Temperatures in 1999 were nearly three-tenths of a degree lower than in 1998, and a similar change should occur this time around, though it might not fit so neatly into a calendar year.

Relevant passages:
Year <=SEP=> A year is the orbital period of the Earth moving in its orbit around the Sun . Due to the Earth 's axial tilt , the course of a year sees the passing of the seasons , marked by changes in weather , the hours of daylight , and , consequently , vegetation and soil fertility . In temperate and subpolar regions around the globe , four seasons are generally recognized : spring , summer , autumn and winter . In tropical and subtropical regions several geographical sectors do not present defined seasons ; but in the seasonal tropics , the annual wet and dry seasons are recognized and tracked .   A calendar year is an approximation of the number of days of the Earth 's orbital period as counted in a given calendar . The Gregorian , or modern , calendar , presents its calendar year to be either a common year of 365 days or a leap year of 366 days , as do the Julian calendars ; see below . For the Gregorian calendar the average length of the calendar year ( the mean year ) across the complete leap cycle of 400 years is 365.2425 days . The ISO standard ISO 80000-3 , Annex C , supports the symbol `` a '' ( for Latin annus ) to represent a year of either 365 or 366 days . In English , the abbreviations `` y '' and `` yr '' are commonly used .   In astronomy , the Julian year is a unit of time ; it is defined as 365.25 days of exactly seconds ( SI base unit ) , totalling exactly seconds in the Julian astronomical year .   The word `` year '' is also used for periods loosely associated with , but not identical to , the calendar or astronomical year , such as the seasonal year , the fiscal year , the academic year , etc. . Similarly , `` year '' can mean the orbital period of any planet : for example , a Martian year or a Venusian year are examples of the time a planet takes to transit one complete orbit . The term can also be used in reference to any long period or cycle , such as the Great Year .

Winter <=SEP=> Winter is the coldest season of the year in polar and temperate climates , between autumn and spring . Winter is caused by the axis of the Earth in that hemisphere being oriented away from the Sun . Different cultures define different dates as the start of winter , and some use a definition based on weather . When it is winter in the Northern Hemisphere , it is summer in the Southern Hemisphere , and vice versa . In many regions , winter is associated with snow and freezing temperatures . The moment of winter solstice is when the sun 's elevation with respect to the North or South Pole is at its most negative value ( that is , the sun is at its farthest below the horizon as measured from the pole ) , meaning this day will have the shortest day and the longest night . The earliest sunset and latest sunrise dates outside the polar regions differ from the date of the winter solstice , however , and these depend on latitude , due to the variation in the solar day throughout the year caused by the Earth 's elliptical orbit ( see earliest and latest sunrise and sunset ) .

Celsius <=SEP=> Celsius , also known as centigrade , is a metric scale and unit of measurement for temperature . As an SI derived unit , it is used by most countries in the world . It is named after the Swedish astronomer Anders Celsius ( 1701 -- 1744 ) , who developed a similar temperature scale . The degree Celsius ( ° C ) can refer to a specific temperature on the Celsius scale as well as a unit to indicate a temperature interval , a difference between two temperatures or an uncertainty . Before being renamed to honour Anders Celsius in 1948 , the unit was called centigrade , from the Latin centum , which means 100 , and gradus , which means steps .   The current scale is based on 0 ° for the freezing point of water and 100 ° for the boiling point of water at 1 atm pressure following a change introduced by Jean-Pierre Christin to reverse the Celsius thermometer scale ( from water boiling at 0 degrees and ice melting at 100 degrees ) . This scale is widely taught in schools today . By international agreement the unit `` degree Celsius '' and the Celsius scale are currently defined by two different temperatures : absolute zero , and the triple point of Vienna Standard Mean Ocean Water ( VSMOW ) , a specially purified water . This definition also precisely relates the Celsius scale to the Kelvin scale , which defines the SI base unit of thermodynamic temperature with symbol K. Absolute zero , the lowest temperature possible , is defined as being precisely 0 K and − 273.15 ° C . The temperature of the triple point of water is defined as exactly 273.16 K at 611.657 Pa pressure .   Thus , the magnitude of one degree Celsius and that of one kelvin are exactly the same and the difference between the two scales ' null points is precisely 273.15 degrees ( and ) .

Eocene <=SEP=> The Eocene ( -LSB- pronˈiːəˌsiːn , _ ˈiːoʊ - -RSB- ) Epoch , lasting from , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era . The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch . The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C . The end is set at a major extinction event called the Grande Coupure ( the `` Great Break '' in continuity ) or the Eocene -- Oligocene extinction event , which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay . As with other geologic periods , the strata that define the start and end of the epoch are well identified , though their exact dates are slightly uncertain .   The name Eocene comes from the Ancient Greek ἠώς ( ēṓs , `` dawn '' ) and καινός ( kainós , `` new '' ) and refers to the `` dawn '' of modern ( ` new ' ) fauna that appeared during the epoch .