Describe the physical properties of the atmosphere, including its composition, density, water vapor content, pressure, and movement

Question

What will be an ideal response?

Answer 1

The composition of dry air is almost entirely of nitrogen and oxygen. The amount of water vapor in air depends in part on the air's temperature. Warm air, for instance, can hold more water vapor than cold air because the air molecules are moving more quickly and come into contact with more water vapor. Thus, warm air is typically moist, and, conversely, cool air is typically dry. Temperature has a dramatic effect on the density of air. At higher temperatures, for example, air molecules move more quickly, take up more space, and density is decreased. Thus, the general relationship between density and temperature is as follows: Warm air is less dense, so it rises; this is commonly expressed as "heat rises." Cool air is more dense, so it sinks. Atmospheric pressure is 1.0 atmosphere (14.7 pounds per square inch) at sea level and decreases with increasing altitude. Air always moves from high-pressure regions toward low-pressure regions. This moving air is called wind.