Climate – a region’s weather conditions average over thousands of years

Includes temperature and moisture averages

1. Average temperature over the year2. Temperature range throughout the

year-difference between the hottest and coldest months of the year

The average yearly precipitation is less than the potential evapotranspiration.

Affected by the temperature – high temperature but low rainfall = arid

Examples - Deserts

Average rainfall is greater than the potential evapotranspiration

A lot of rain is not needed…as long as there is more rain than evapotranspiration

Examples - rainforest

Latitude – affects the temperature

Near poles – (high latitude) the angle of the sun changes a lot during the year, creating a wide temperature range, but cooler temperatures overall

Near equator – (low latitude) the angle of the sun is high most of the year, creating steady but warm temperatures all year long.

Latitude - affects moisture

Low pressure areas near equator and mid latitudes creates warm rising air, clouds and precipitation

High pressure areas near poles and 30o create dry sinking air and deserts.

See ESRT diagram wind and moisture belts

Large Bodies of Water -Marine climate –

Wind blows moist air from over the ocean of large lakes. Being near water will also make temperatures fluctuate less during year than an inland area of similar latitude (cooler summers and warmer winters) like Long Island

Large Bodies of Water –Continental climate –

Wind blows dry air over vast stretches of land. Being inland (far from water) will also make temperatures fluctuate more during year than an marine location of similar latitude (hotter summers and colder winters) like St. Louis.

Prevailing winds blow air masses across the US from southwest to Northeast (west to east)West coast – receives warmer wet air

(marine) East coast – mostly receives dryer air

(continental) except for Long Island (marine)

Lake effect snow – near great lakes in upstate NY because of wet air being clown from the great lakes

Ocean Currents Warmer water from the equator carried to higher

latitudes

Cooler water from near poles carried toward equator

See ESRT Surface Ocean Currents

ElevationHigher elevation have cooler

temperatures and more moisture because of increased cooling of the air and more condensation

Examples – Catskill and Adirondacks in NY

Mountains Mountains can block cold or warm air passing Windward side – “water” or “wet” side forces

air up and to condense, creating precipitation “Leeward side – “land” or “dry” side because

once the air passes over the mountain it descends, warms and precipitation stops. Examples –Champlain Lowlands are on the

leeward side of Adirondack Mountains. Also, Las Vegas desert is on the leeward side of the Sierra Nevadas.

Cloud Cover – Clouds near the

equator block some insolation, making it slightly cooler than the 30o latitude dry, cloudless areas.

Pollution adds particles to air that increases condensation, creating haze or clouds which decrease the transparency of the air (i.e cools it off)

Vegetation – Plants and trees increase transpiration, making areas humid and cooler from shade.

When deforestation occurs, the area gets much hotter and dryer

Jan. 2011 Regents