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