Meteorology is the study of all atmospheric phenomena, but it tends to direct most of its attention to the weather. The term "weather" refers mainly to atmospheric phenomena that change over a short time scale, including temperature, precipitation, wind, barometric pressure, humidity, cloud classification and so on. Climatology on the other hand is the study of the long-term effect that weather has on a particular place or area.

The Earth's atmosphere is a very active environment. Solar radiation, cosmic rays, the Earth's rotation, temperature, elevation--these are all part of a long list of factors that bring about change in the atmosphere. Almost all weather activity takes place in the troposphere, the 9 miles (15 km) of air closest to the Earth's surface. What goes on in this region of the atmosphere most directly affects the Earth's inhabitants. Until relatively recent times, weather was interpreted as a manifestation of the wrath...