Pre Test 1. True or False. Earths Surface tempature has been constantly changing in geological time. 2. How does earth exchange energy with the enviroment? 3. How does earth receive energy from the sun? 4. What does visible solar energy turn into once it is absorbed by the clouds? 5. What does GHG stand for?

SECTION 3 Radiative Balance and the Natural Greenhouse Effect

Natural Greenhouse Effects The Earth’s temperature has stayed remarkably constant through the geological time periods The most recent ice age the average global surface temp. has only risen about 3 d.C

Radiation Any form of matter can emit forms of radiation as long as the temp stays above Absolute Zero The Earth emits radiation at a lower wavelength(lower energy levels) than the Sun

Natural Greenhouse Effect Some of the infrared rays that reflect off the Earths surface and are outgoing become trapped within the Earths atmosphere and cause the Greenhouse Effect Ex. of Gases: Nitrogen, Oxygen, and Argon (most abundant). Carbon Dioxide, Methane, and Nitrous Oxide (Rarer GHGs)

Radiation and Gas Earth’s surface temperature was relatively constant because it radiates energy back to space at a rate nearly equal to the energy input it receives from the Sun. Sun emits solar radiation to the Earth and Earth radiates heat back to space at longer wavelengths. When solar radiation reaches Earth, it is absorbed by clouds, atmosphere, or the surface. Some infrared energy that is radiated from Earth is trapped in the atmosphere through the “greenhouse effect”. Nitrogen, oxygen, argon neither absorb nor emit radiation. Clouds, water vapor, and other GHG’s absorb long-wave radiation. These gases radiate energy both to space and to Earth.

- EARTH EXCHANGES ENERGY WITH ENVIRONMENT THROUGH ELECTROMAGNETIC RADIATION - SIMULTANEOUSLY ABSORBING ENERGY FROM SUN (SOLAR RADIATION) AND GIVING OFF ENERGY INTO SPACE - WHEN SOLAR RADIATION HITS EARTH, IT IS TRANSFORMED INTO HEAT ENERGY, RAISING TEMPERATURE & EARTH EMITS INFRARED RADIATION BACK TO OUTER SPACE - SOME OUTGOING INFRARED ENERGY IS TRAPPED IN EARTH’S ATMOSPHERE THROUGH PROCESS CALLED “GREENHOUSE EFFECT” - GREENHOUSE GASES RADIATE ENERGY BOTH TO EARTH (WARMS SURFACE) AND TO SPACE - HEAT RECEIVED BY SURFACE OF EARTH IS 3X LARGER THAN RECEIVED BY SOLAR RADIATION BECAUSE OF NATURAL GREENHOUSE EFFECT Radiative Balance and the Natural Greenhouse Effect

Post Test 1. Name three types of GHG? 2. What was the temperature change during the most recent ice age? 3. Explain the green house effect. 4. True or False, Earth emits radiation at a higher wavelengths than the sun 5. How does earth exchange energy with the environment?