22.2
Solar Energy and the Atmosphere
What happens to incoming
solar radiation?
1. Scattered
2. Reflected
3. 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
3. Some
escapes
back to
space
1. Short
wavelength
IR comes in
2. Earth absorbs short
wavelength IR and readmits
it as a longer wavelength IR
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
• More direct rays equal
warmer temperatures
3. Season
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