Ch. 26.2 Climate ZonesCh. 26.2 Climate Zones

• Three main climate zones on earth; tropical climates around the equator, middle latitude climates, and polar climates.

Tropical ClimatesTropical Climates

• Avg. monthly temp. of at least 18o C year round.

• Different climates within climate zones based on annual precipitation.

• Tropical Rain Forest—within 5 to 10 degrees of the equator; dense vegetation, over 250 cm of rain a year, yearly temperature range of about 3 degrees C.

• Tropical Desert Climate—20 to 30 degrees N. and S. latitude; influenced by sinking, warming, dry air; annual rainfall less than 25 cm.

• Tropical Savanna Climate—between tropical rain forests and tropical deserts.

• Shifting precipitation belts result in wet summers and dry winters.

• Open grasslands with scattered trees and shrubs.

Polar ClimatesPolar Climates

• Average monthly temp. never higher than 10 degrees C.

• Occur between 55 degrees latitude and the poles.

• Subarctic Climate—between 55 and 65 degrees N. latitude.

• Yearly precipitation of 25 to 50 cm.

• Evergreen forests can grow due to low evaporation.

• Severe winters and short summers.

• Large annual temperature range.

• Tundra Climate—named for tundra vegetation…mosses, lichens, small flowering plants…no trees.

• Lower temperature range due to moderating influence of nearby oceans.

• Warmest months average only 4 degrees C.

• 25 cm precipitation yearly, mostly snow.

Middle Latitude ClimatesMiddle Latitude Climates

• Latitude ranges from contiguous United States to southern Canada. Uneven precipitation in different regions result in several different climates.

• Marine West-Coast Climate—40 to 60 degrees N. latitude in Pacific NW. Cool moist air from the ocean causes 60 to 150 cm precipitation. Temp. range from 7 to 20 degree C.

• Mediterranean Climate—between 30 and 40 degrees latitude. Wet winters and dry summers. 40 cm avg. precipitation. Temp. range from 14 to 21 degrees C.

• Middle-Latitude Desert—less than 25 cm precipitation, and cold winters. Shrubs and cacti. 35 to 50 degrees N. latitude.

• Steppe Climate—same latitude as mid latitude deserts, but at higher elevations. 25 to 50 cm precipitation / yr. Grass type vegetation, and high temp. range.

• Humid Continental—warm humid summers with very cold winters. Violent weather conditions due to colliding air masses.

• Humid Subtropical—influenced by moist ocean air in summer. Heavy rains and hurricanes. Southeast USA.