1. Unit 3 Notes Part 4: Greenhouse Effect

2. What is the Greenhouse Effect?
The warming of the Earth due to an atmosphere.
The greenhouse effect causes an increase in the temperature of a planet as heat energy from sunlight is trapped by the gaseous atmosphere.

3. How does the Greenhouse Effect work?
Solar Energy (sunlight) is short-wavelength radiation which easily penetrates the Earth's atmosphere and warms the Earth
Only about one quarter of incoming sunlight is reflected by the atmosphere.

4. How does the Greenhouse Effect work?
The warmed Earth emits
long-wavelength radiation
(infrared waves or heat
energy) back into space
These longer waves are
mostly absorbed by
greenhouse gasses,
trapping the energy.
Some energy is reradiated back to Earth.

5. What happens to the incoming solar radiation as it passes through Earth’s atmosphere?
Incoming solar radiation is made up of some UV and infrared, but is mostly visible light
70-75% makes it through the atmosphere
UV is absorbed by ozone
Infrared is absorbed by water vapor
Water Vapor
Carbon Dioxide
Oxygen and Ozone
Methane
Nitrous Oxide
Rayleigh Scattering

6. What happens to the outgoing thermal radiation as it travels from Earth’s surface toward space?
The energy absorbed by the surface is radiated from the Earth as longwave radiation
15-30% makes it out to space
Some of this is absorbed by water vapor, followed by CO2, methane, and nitrous oxide

7. Describe the major “greenhouse gases?”
Water vapor, which causes about 36-70% of the greenhouse effect on Earth (not including clouds)
Carbon Dioxide, which causes 9-26%
Methane, which causes 4-9%
Ozone, which causes 3-7%
Nitrous Oxide
This animation shows how a carbon dioxide molecule vibrates when it absorbs heat. Courtesy of UCAR (LEARN and COMET)