Query: The data is being reported by the University of Illinois's Arctic Climate Research Center, and is derived from satellite observations of the Northern and Southern hemisphere polar regions (Daily Tech).

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Snow <=SEP=> Snow pertains to frozen crystalline water throughout its life cycle , starting when it precipitates from clouds and accumulates on surfaces , then metamorphoses in place , and ultimately melts , slides or sublimates away . Snowstorms organize and develop by feeding on sources of atmospheric moisture and cold air . Snowflakes nucleate around particles in the atmosphere by attracting supercooled water droplets , which freeze in hexagonal-shaped crystals . Snowflakes take on a variety of shapes , basic among these are platelets , needles , columns and rime . As snow accumulates into a snowpack , it may blow into drifts . Over time , accumulated snow metamorphoses , by sintering , sublimation and freeze-thaw . Where the climate is cold enough for year-to-year accumulation , a glacier may form . Otherwise , snow typically melts seasonally , causing runoff into streams and rivers and recharging groundwater .   Major snow-prone areas include the polar regions , the upper half of the Northern Hemisphere and mountainous regions worldwide with sufficient moisture and cold temperatures . In the Southern Hemisphere , snow is confined primarily to mountainous areas , apart from Antarctica .   Snow affects such human activities as transportation : creating the need for keeping roadways , wings , and windows clear ; agriculture : providing water to crops and safeguarding livestock ; such sports as skiing , snowboarding , snowmachine travel ; and warfare : impairing target acquisition , degrading the performance of combatants and materiel , and impeding mobility . Snow affects ecosystems , as well , by providing an insulating layer during winter under which plants and animals are able to survive the cold .

Extratropical cyclone <=SEP=> Extratropical cyclones , sometimes called mid-latitude cyclones or wave cyclones , are low-pressure areas which , along with the anticyclones of high-pressure areas , drive the weather over much of the Earth . Extratropical cyclones are capable of producing anything from cloudiness and mild showers to heavy gales , thunderstorms , blizzards , and tornadoes . These types of cyclones are defined as large scale ( synoptic ) low pressure weather systems that occur in the middle latitudes of the Earth . In contrast with tropical cyclones , extratropical cyclones produce rapid changes in temperature and dew point along broad lines , called weather fronts , about the center of the cyclone .

Cryosphere <=SEP=> The cryosphere ( from the Greek κρύος kryos , `` cold '' , `` frost '' or `` ice '' and σφαῖρα sphaira , `` globe , ball '' ) is those portions of Earth 's surface where water is in solid form , including sea ice , lake ice , river ice , snow cover , glaciers , ice caps , ice sheets , and frozen ground ( which includes permafrost ) . Thus , there is a wide overlap with the hydrosphere . The cryosphere is an integral part of the global climate system with important linkages and feedbacks generated through its influence on surface energy and moisture fluxes , clouds , precipitation , hydrology , atmospheric and oceanic circulation . Through these feedback processes , the cryosphere plays a significant role in the global climate and in climate model response to global changes . The term deglaciation describes the retreat of cryospheric features . Cryology is the study of cryospheres .

Precipitation <=SEP=> In meteorology , precipitation is any product of the condensation of atmospheric water vapor that falls under gravity . The main forms of precipitation include drizzle , rain , sleet , snow , graupel and hail . Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor , so that the water condenses and `` precipitates '' . Thus , fog and mist are not precipitation but suspensions , because the water vapor does not condense sufficiently to precipitate . Two processes , possibly acting together , can lead to air becoming saturated : cooling the air or adding water vapor to the air . Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud . Short , intense periods of rain in scattered locations are called `` showers . ''   Moisture that is lifted or otherwise forced to rise over a layer of sub-freezing air at the surface may be condensed into clouds and rain . This process is typically active when freezing rain is occurring . A stationary front is often present near the area of freezing rain and serves as the foci for forcing and rising air . Provided necessary and sufficient atmospheric moisture content , the moisture within the rising air will condense into clouds , namely stratus and cumulonimbus . Eventually , the cloud droplets will grow large enough to form raindrops and descend toward the Earth where they will freeze on contact with exposed objects . Where relatively warm water bodies are present , for example due to water evaporation from lakes , lake-effect snowfall becomes a concern downwind of the warm lakes within the cold cyclonic flow around the backside of extratropical cyclones . Lake-effect snowfall can be locally heavy . Thundersnow is possible within a cyclone 's comma head and within lake effect precipitation bands . In mountainous areas , heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation . On the leeward side of mountains , desert climates can exist due to the dry air caused by compressional heating . The movement of the monsoon trough , or intertropical convergence zone , brings rainy seasons to savannah climes .   Precipitation is a major component of the water cycle , and is responsible for depositing the fresh water on the planet . Approximately 505000 km3 of water falls as precipitation each year ; 398000 km3 of it over the oceans and 107000 km3 over land . Given the Earth 's surface area , that means the globally averaged annual precipitation is 990 mm , but over land it is only 715 mm . Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes .   Precipitation may occur on other celestial bodies , e.g. when it gets cold , Mars has precipitation which most likely takes the form of frost , rather than rain or snow .