Climate and Terrestrial Biodiversity

Chapter 7

7-1 What Factors Influence Climate?

Concept 7-1 An area's climate is determined mostly by solar radiation, the earth’s rotation, global patterns of air and water movement, gases in the atmosphere, and the earth’s surface features.

Weather is a local area’s short-term physical conditions such as temperature and precipitation.

Climate is a region’s average weather conditions over a long period of time.

“Climate is what we expect, weather is what we get.”

-- Mark Twain

7-1 What Factors Influence Climate?

Climate varies from place to place because the air circulation in the lower atmosphere due to:

1. Uneven heating of the earth’s surface by the sun

2. Rotation of the earth on its axis

3. Properties of air, water, and land

7-1 What Factors Influence Climate?

1. Uneven heating of Earth’s surface by the sun:• Equator vs. poles – round planet• Earth’s tilt – 23.5º• Albedo – how strongly it reflects light• Insolation – solar radiation received

by a given area in a given time (kWh/m2/day)

7-1 What Factors Influence Climate?

7-1 What Factors Influence Climate?

2. Rotation of Earth on its axis:• Rotation is FASTER at equator than poles…

causes the Coriolis Effect – the deflecting of air masses by the rotation of the Earth

• Also causes complex global air circulation• Wind belts produce ocean surface currents

7-1 What Factors Influence Climate?

If the Earth didn’t rotate, we could expect wind to flow in the following manner…

7-1 What Factors Influence Climate?

Instead it looks like this…

7-1 What Factors Influence Climate?

3. Properties of air, water, and land:• Convection cells form due to

interaction between air/water/land

7-1 What Factors Influence Climate?

7-1 What Factors Influence Climate?

Heat and moisture are distributed over the earth’s surface by vertical air currents, which form six giant convection cells at different latitudes.

7-1 What Factors Influence Climate?

Ocean Currents are caused by:• Prevailing wind belts• Earth’s rotation

7-1 What Factors Influence Climate?

Ocean currents influence climate by distributing heat from place to place.

The temp. of the water affects the temp. of the air

Generalized Map of the Earth’s Current Climate Zones

7-1 What Factors Influence Climate?

The Greenhouse effect keeps the entire planet warmer than it would be without it

Greenhouse gases: • Water vapor – H2O

• Carbon Dioxide – CO2

• Methane – CH4

• Nitrous Oxide – N2O

7-1 What Factors Influence Climate?

The Rain Shadow Effect

Interactions between land and oceans and disruptions of airflows by mountains and cities affect local climates.

Microclimate – local and regional climates different than the larger regional climate

7-1 What Factors Influence Climate?

7-2 How Does Climate Affect the Nature and Locations of Biomes?

Concept 7-2 Differences in average annual precipitation and temperature lead to the formation of tropical, temperate, and cold deserts, grasslands, and forests, and largely determine their locations.

Climate Affects Where Organisms Can Live

Biomes – large terrestrial regions characterized by similar climate, soil, plants, and animals

• Biomes vary by, and are determined by:

• Latitude and elevation

• Annual precipitation

• Temperature

7-2 How Does Climate Affect the Nature and Locations of Biomes?

7-2 How Does Climate Affect the Nature and Locations of Biomes?

Generalized Effects of Elevation and Latitude on Climate and Biomes

7-2 How Does Climate Affect the Nature and Locations of Biomes?

Average Precipitation and Average Temperature as Limiting Factors

7-2 How Does Climate Affect the Nature and Locations of Biomes?