Climate Regions and Influencing Factors

 Weather: the condition of the bottom layer of the earth’s atmosphere over a short time period  Includes temp., precipitation, and wind  Climate: the weather pattern an area typically experiences over a long time period  “Climate is what you expect; weather is what you get”

 Relationship to the sun  Latitude  Wind & ocean currents  Precipitation  Water bodies & landforms  Elevation

 Sun = major source of climates  Greenhouse effect  Small amount of sun’s radiation reaches earth  Atmosphere traps heat, allowing organisms to grow  Rotation : spin of the earth on its axis (24 hrs)  Revolution : complete orbit around the sun (365 ¼ days)  Tilt = 23 ½ degrees  Area between Tropic of Cancer (23.5°N) & Tropic of Capricorn (23.5°S) receives the most direct sunlight

 Seasons  North Pole tilted in towards the sun = summer in the Northern hemisphere  More direct sunlight to that hemisphere  Longer, warmer days  Summer solstice (June 21) & winter solstice (December 21) mark the change of season  Sun is directly overhead at T. of Cancer & Capricorn  Vernal & autumnal equinoxes (March 21 & September 23)  Sun is directly overhead at the Equator  Length of day & night are near equal

 Because of tilt & path of sun’s rays, latitude impacts climate  How far a place is from the Equator dictates temp.  Low latitudes (0-23.5°N, °S)  “Tropics”; hot year-round  Ex: Sierra Leon (Africa)  Middle latitudes ( °N, °S)  “Temperate”; cooler than tropics, wide variety of temps  Ex: Pennsylvania (U.S.)  High latitudes (66.5°N-N.pole, 66.5°S-S.pole)  “Polar”; consistently cold; mostly indirect sunlight  Ex: Northwest Terr. (Canada)

 Sun’s heat distributed by convection  Heat rises, creates circular motion  Air & water moves in this way: air = wind, water = currents  Wind  Warm air rises (low pressure zones) & moves towards the poles; cool air sinks (high pressure zones) & moves towards the Equator  *Winds are named for the direction of origin (i.e. “westerlies” come from the west)

 Ocean currents  Follow similar pattern as wind  Cold water moves poles  Equator; warm water moves Equator  poles

 Precipitation = all forms of water that fall from the atmosphere  Timing & volume  climate type  Warm air absorbs moisture; when it cools, excess moisture condenses into liquid  clouds  precipitation  3 types: convectional, orographic, frontal

 Convectional  Air rises because it is hot & humid  cooling  precipitation  Common in tropical climates near the Equator  Orographic  Air rises because it is forced up over high landforms  cooling  precipitation  Common in coastal areas  Creates windward & leeward sides of mtn ranges  Frontal  Air rises because it meets a front of cooler air that pushes it up  cooling  precipitation

 Coastal & inland mountains  Deserts  Forests  Even tall buildings  All can change air flow, precip. patterns, & climate  Water bodies  Wind that crosses water takes on its temperature  milder climates in nearby land areas  Temp. is changed by warm or cool air & water currents

 Stronger determinant of climate than latitude in places with very high elevation  Ex: Mt. Kilimanjaro in Tanzania (4°S, >19,000 ft)  Air temp. decreases ~3.5° per 1,000 ft of elevation