| A | B |
|---|
| troposphere | the bottom layer of the atmosphere |
| thermosphere | the hottest layer of the atmosphere |
| mesosphere | the layer of the atmosphere where many meteors burn up |
| stratosphere | the layer of the atmosphere containing ozone |
| air mass | a large volume of air with about the same temperature, pressure, and humidity |
| air pressure | the weight of the air pressing down on an area |
| relative humidity | the amount of moisture in the air compared with the amount that could be there |
| front | a place where two different air masses meet |
| forecast | a prediction of what the weather will be in the future |
| station model | an arrangement of numbers and symbols that tells the weather around a weather station |
| surface map | a map that includes station models, fronts, and high-and low-pressure areas |
| weather balloon | carries weather instruments aloft to about 30,000 meters |
| weather map | shows recent weather conditions over a large area |
| thunderstorm | a strong storm containing thunder and lightning |
| hurricane | a severe storm over tropical waters with spiraling winds of at least 119 km/hr |
| tropical storm | a low-pressure storm over the ocean with spiraling winds of at least 63 km/hr |
| tornado | an intense, spiraling windstorm that forms from thunderstorms |
