World Book Trivia Challange--9/24-weather

Humidity is a measure of the amount of water vapor in the air. There is an upper limit to this amount. Air that contains its maximum amount of water vapor is described as saturated. The amount of water vapor the air can hold increases as the air temperature rises. The capacity decreases as the temperature falls. Thus, saturated warm air has more water vapor than saturated cold air.

A geostationary satellite orbits about 22,300 miles (35,900 kilometers) above the equator. It travels eastward at the same rate as Earth rotates. Thus, a geostationary satellite remains above the same point on the equator. Because geostationary satellites orbit at such a high altitude, they can record images that cover a wide area. For example, two of them cover most of the United States and Canada. Most satellite images shown on televised weather reports come from this type of satellite.

From time to time, scientists have tried to alter the weather. They have tried to modify hurricanes, suppress hailstorms, and clear fog. Most of these efforts have not worked. Today, scientists focus their weather modification efforts primarily on cloud seeding. Cloud seeding is an attempt to stimulate the natural precipitation-forming process.

In the greenhouse effect, certain gases in the atmosphere trap heat from the sun. They act much like the glass roof and walls of a greenhouse. The heat-trapping gases are called greenhouse gases. They include methane (CH4), nitrous oxide (N2O), and ozone (O3). But the gas that has produced the most warming is carbon dioxide (CO2).

Earth is not the only planet with a variety of weather conditions. All of the planets in the solar system larger than Mercury have enough of an atmosphere to support weather systems. In addition, the moons Titan and Triton have such an atmosphere.

Climates vary from place to place because of five main factors—latitude (distance from the equator), altitude (height above sea level), topography (surface features), distance from oceans and large lakes, and the circulation of the atmosphere. The type of animals and plants depends on the climate, not the other way around.

The International Meteorological Organization was renamed the World Meteorological Organization (WMO)when it became part of the United Nations. The birthdate of the organization, March 23, is recognized as World Meteorological Day by the United Nations members.

Meteorologists classify weather systems according to their size and how long they last. The two largest and longest-lasting types of systems are planetary-scale systems and synoptic-scale systems. Two briefer and smaller types of systems are mesoscale systems and microscale systems. Mesoscale systems may last an hour or less.

The most plentiful gas is nitrogen. Nitrogen accounts for about 78 percent of the air we breathe. The second most plentiful gas is oxygen, at 21 percent. The remaining 1 percent consists of a variety of gases.

Air temperature is a measure of the energy of motion of the air's gas molecules. The factors most responsible for the heating and cooling of the atmosphere are radiation arriving from the sun and radiation flowing from Earth.