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Climate

Weather Climate Climatology Condition of the atmosphere at a particular place and time Average, year after year conditions of temperature, precipitation, rainfall, winds, clouds, etc. in an area Two main factors – temperature & precipitation Study of the world’s climates & long term weather

Climate Controls Conditions that influence the climate of an area

Climate Controls Factors affecting Temperature Latitude Altitude/elevation Distance from large bodies of water Ocean currents

Latitude 3 main zones Distance from the equator measured in degrees Closer to the equator – receive more solar radiation Global winds move hot air away from the equator Tropical – located from equator to 23.5O north or south of the equator Temperate – located 23.5O to 66.5O north and 23.5O to 66.5O south latitudes Polar – located 66.5O to 90O north and 66.5O to 90O south latitudes.

Tropical zone Temperate Zone Polar Zone

Altitude Temperature decreases 6.5o C/km in the troposphere Ex. Mt. Kilimanjaro in Africa is ~6km tall, so ~39oC (102oF) colder air than at sea level

Distance from H2O Ocean and large lakes affect temperatures H2O greatly moderates temperature of nearby land Land near coastal areas has mild marine climates results in warm winters and cools summers Interior lands has harsher continental climates results in hot summers and cold winters

Ocean Currents Patterns of ocean waters that move in regular patterns Heavily influence weather along coastal communities Ex. California current, Gulf Stream, North Atlantic Drift

Seasons Cause Tilt of the earth as it rotates around the sun Tilt is 23.5o toward the North Star or Polaris Greater the tilt, the greater the differences between summer and winter climates

Classifying Climates Classification Climates are classified based on Temperature and Precipitation

Classifying Climates Classification Based on work by Koppen around 1900 Divided into 6 main climate categories Tropical rainy Dry Temperate Marine Temperate Continental Polar

Koppen Classifications Tropical Rainy Tropical Wet & Dry Many days are rainy w/ afternoon thundershowers Rain falls year round Forest have tall trees with many hardwood species Only Hawaii has a tropical wet climate >10M rain/yr Slightly less rain than Tropical rainy Typical of Savannas or grasslands of Africa Only southern tip of Florida is Tropical Wet & Dry

Koppen Classifications Dry Arid Semiarid Amount of water is less than what amount that could potentially evaporate Two classification - Arid & Semi-Arid Areas that get less than 25cm rain/year Include most deserts Areas located along the regions of deserts – called Steppes Have sufficient water for small brush and grasses to grow Ex. Great Plains

Koppen Classifications Marine West Coast Coolest marine temps found north and south of 40o latitude Large amounts rain & snow Thick forest of fir, redwoods, & cedar

Koppen Classifications Mediterranean Drier & warmer then west coast climate Southern California coast is Mediterranean climate Two main vegetation types – dense shrubs and small trees Agriculture is highly important in this climate

Koppen Classifications Humid Subtropical Wet & warm, but not as hot as tropics Ex. Houston, New Orleans, Atlanta Summers are hot, but winters can bring freezing temperatures from polar air masses Mixed forests of oak, hickory, ash along with cotton and other farm commodities

Koppen Classifications Polar Coldest region Includes the ice cap and tundra regions Characterized by permafrost – permanently frozen soil

Long-Term Climate Changes Why study climate? How? Document plant & animal changes Understand cultural moves Pollen – tells the types of ancient plants Tree rings – tells what changes have happened short term (3,000-4,000) in the climate Thin indicate short water years, thick indicate good water years Ice Ages – good for 100,000 years Scientist know that warm interglacial period exist between ice ages Last ice age ended ~10,500 years ago

Causes of Climate Change Position of earth relative to sun Changes in the amount of energy from the sun – sun spot activity Movement of the continents – plate tectonics Global warming – greenhouse effect Ozone depletion by CFCs

Climate Video