Sunlight Penetrating the Atmosphere

1
Sunlight Penetrating the Atmosphere
9.1 Energy from the Sun
2
A Blue Sky
9.1 Energy from the Sun

• Blue, indigo, and violet light is absorbed and
  reflected as it passes through the atmosphere.

• The sky appears blue when blue light scatters and
  reaches our eyes.

3
A Red Sunset
9.1 Energy from the Sun

• As the Sun sets, light travels a longer path
  through Earths atmosphere.

• Longer wavelengths (yellow, orange) are
  reflected, leaving only the longest wavelength,
  red, to reach our eyes.

4
A Black Sky
9.1 Energy from the Sun

• Since space has no atmosphere to reflect or
  scatter any light, the sky would appear black.

5
The Suns Power
9.1 Energy from the Sun

• Solar heating provides energy to warm Earth.

• Solar radiation is constant and uniform, but is
  not evenly distributed on Earth.

6
Suns Energy on Earth
9.1 Energy from the Sun

• The Suns energy serves as the power for air
  currents, weather systems, and the water cycle.

• Energy from the sun can be harnessed directly and
  indirectly.

The Water Cycle
7
Convection
9.2 Energy Transfer in the Atmosphere

• Convection moves hot air that is near the Earths
  surface to higher altitudes.

• In a convection current, hot air rises and cold
  air sinks due to differences in density.

• Convection currents distribute heat energy within
  the troposphere.

8
Radiation
9.2 Energy Transfer in the Atmosphere

• Radiation is the form of heat transfer that warms
  the Earth.

• Different molecules absorb radiation with
  different wavelengths.

• Every object in the universe emits radiation as
  long as it has a temperature above absolute
  zero.

9
Greenhouse Gases
9.2 Energy Transfer in the Atmosphere

• Greenhouse gases such as water vapor, methane
  (CH4), and carbon dioxide are responsible for a
  large percentage of the additional warming of
  Earths surface.

• Global warming is the process in which the
  average surface temperature increases.

Global Warming
10
Greenhouse Gases (cont.)
9.2 Energy Transfer in the Atmosphere
11
Greenhouse Gases (cont.)
9.2 Energy Transfer in the Atmosphere
12
Uneven Heating of Earths Surface
9.3 Air Currents

• Uneven heating of Earths surface by the sun
  causes differences in air pressure which causes
  wind.

• Materials on Earths surface absorb or reflect
  different amounts of sunlight.

13
Percent of Reflection of Solar Radiation
9.3 Air Currents
14
Uneven Heating of Earths Surface (cont.)
9.3 Air Currents

• Differences in materials on the Earths surface
  cause the air to heat unevenly resulting in
  convection currents.

15
Updrafts
9.3 Air Currents

• As land becomes warm, it warms the air above it.

• An updraft, or thermal, occurs as the air is
  heated and it expands becoming less dense than
  the surrounding air.

16
Downdrafts
9.3 Air Currents

• A downdraft, or sinking column of air, occurs
  when dense air sinks toward Earths surface.

17
Global Convection Currents
9.3 Air Currents

• In the one cell model, Earths atmosphere
  circulated in a large convection cell in each
  hemisphere.

• The three cell model more accurately describes
  Earths atmosphere.

18
End of Resources