ABOUT GLOBAL WARMING: Global warming refers to an increase in the earth's average temperature -- which has risen about 1 degree F over the past 100 years. A warmer earth may lead to changes in rainfall patterns, and a rise in sea level, for example, as polar glaciers melt. Some of this rise is due to the greenhouse effect: certain gases in the atmosphere trap energy from the sun so that heat can't escape back into space. Without the greenhouse effect, the earth would be too cold for humans to survive, but if it becomes too strong, the earth could become much warmer than usual, causing problems for humans, plants and animals.
TYPES OF CLOUDS: Most clouds are a combination or variation of three basic types. Stratus clouds are horizontal layered clouds that stretch out across the sky like a blanket, They often form at the boundary where a layer of warm moist air passes over a layer of cool air, causing the warm air to cool. If the warm air cools below the dew point, the excess water vapor condenses to form the blanket-like layer of stratus clouds. Cumulus clouds are puffy and look like giant cotton balls. The usually form when warm moist air is forced upward, cooling as it rises. Again, if it cools before the dew point, condensation will occur.
p>The American Geophysical Union and the American Meteorological Society contributed to the information contained in the TV portion of this report.