22.2 Solar Energy and the Atmosphere

What happens to incoming solar radiation?

1. Scattered2. Reflected3. Absorbed

Scattering

• Clouds, dust, and water vapor scatter sunlight.

• Causes rays to travel in all directions without changing wavelength.

• Makes sky appear blue!

Why is the sky red/orange at sunrise and sunset?

• Sunlight travels through a longer path in the atmosphere.

• Blue light gets scattered away first (short wavelength) and red is left (long wavelength).

Reflection• Albedo- the

fraction of solar radiation that is reflected by a surface.

Absorption

1. Short wavelength IR comes in

2. Earth absorbs short wavelength IR and readmits it as a longer wavelength IR

3. Some escapes back to space

4. Some IR is absorbed by gasses in atmosphere (CO2, Water Vapor, NOx, CH4 )and sends it back to earth

Global Warming

What causes changes in temperature?

1. Time of Day• Warmest hours of day are mid to late afternoon.• Earth needs time to absorb sunlight and reradiate it as

heat.

2. Latitude 3. Season

• More direct rays equal warmer temperatures

4. Amount of Water Vapor• Mountains are warm during

day but cold at night due to thinner air with less water vapor

• Deserts are warm during day and cold at night

5. Located near water• Have more moderate

temperatures.• Cooler during day and

warmer at night.

6. Wind Patterns• Land that gets a breeze

from the ocean will be cooler than a breeze from over land