Earth’s climate and how it changes

What Factors Affect Climate? Latitude – distance north or south of equator Elevation – height above sea level Topography – features on land Water Bodies – lakes and oceans Atmospheric Circulation – global winds Vegetation – type and amount of plants

LATITUDE Sun strikes Earth’s surface at different angles creates variations in climate

Climate Zones Differences in solar energy create climate zones Tropical zones Warm all year, 23.5o north to 23.5o south of equator Temperate zones Hot summers and cold winters, 23.5o to 66.5o north and south of equator Polar zones Cold all year, 66.5o north and south to the poles

Energy Transfer Less solar energy is transferred into atmosphere in polar regions than in tropics Differences in energy affects weather and climate Pressure differences produce winds Affects evaporation rates, cloud formation, air masses, and storms

ELEVATION Elevation increases, temperature decreases approximately -6.5oC every 1000 meters or -44oF every 3,281 feet Elevation also determines the amount of precipitation answer: How does elevation affect temperatures and precipitation? Why? Mt. Whitney and the Owens Valley, Eastern California

Can create a Rain Shadow Effect TOPOGRAPHY Can create a Rain Shadow Effect Humid air moves up a mountain: cools, forms clouds, then precipitates Moisture is lost, very dry on other side Think: Can you name a mountain range with a Rain Shadow Effect ?

WATER BODIES AND ATMOSPHERIC CIRCULATION Temperature of water influences atmosphere above it. Water has a higher heat capacity than land. Global winds distribute heat and moisture around Earth Look up the term heat capacity

VEGETATION Temperature – vegetation influences how much of sun’s energy is absorbed and released Precipitation - plants release water vapor and particles into the air creating clouds (the more plants the more humid it is). Consider: how do you think cutting down the rain forest in Brazil has affected the climate there?

Earth’s Orbital Motion Changes in the shape of Earth’s orbit and the tilt of its axis affects global climates How elliptical the orbit is varies every 100,000 to 400,000 years Every 20,000 to 40,000 years the tilt of the axis changes about 3° (less tilt = less difference between seasons) Notice: how has the Sahara desert changed in the last 8,000 years?

Solar Activity Over a short time scale: changes in the amount of solar radiation change global climate. More sun spots indicate a warmer sun that causes warming periods on Earth Fewer sun spots occurred in the 1600’s during the “little ice age” in Europe.

Volcanic Eruptions In the short term volcanic eruptions cause cooling from ash, dust and sulfur- containing particles reflecting sunlight back into space (aerosols). In the long term it can cause warming by increasing CO2 levels

The Greenhouse Effect The Greenhouse Effect is the warming of the atmosphere by gasses that trap solar radiation. Water vapor, CO2, and methane are the major greenhouse gasses Consider: how would increasing methane levels in the atmosphere affect the Earth’s temperature?

Summary Write a 5-8 sentence summary of the factors that affect climate and climate change.