| A | B |
|---|
| El Nino | a warm water event that occurs in the tropical Pacific Ocean once every 2 to 7 years -- can cause dramatic climate changes |
| Polar air mass | a cold air mass that forms north of 50 degrees north latitiude or south of 50 degrees south latitude and has high air pressure |
| air mass | a body of air with about the same temperature,humidity, and pressure |
| anticyclone | high pressure center of dry air |
| cold front | occurs when a rapidly moving cold air mass runs into a slowly moving warm air mass - these usually bring cool dry air, clear skies, and cooler temperatures |
| continental air mass | a dry air mass that forms over land |
| cumulonimbus clouds | fast rising clouds that ususally signal severe thunderstorms |
| cyclone | a swirling center of a low air pressure |
| evacuate | to be moved away from a dangerous situation or area |
| flash flood | a sudden, violent flood that occurs within a few hours, or even minutes, of a heavy rainstorm |
| front | the area where air masses meet and do not mix |
| hurricane | a tropical storm that has winds of 119 km per hour or higher, typically 600 km across |
| isobars | lines joining places on a weather map that have the same air pressure |
| isotherms | lines joining places on a weather map that have the same temperature |
| lightning | a sudden spark, or energy discharge, caused when electrical charges jump between parts of a cloud or between a cloud and the ground |
| maritime air mass | a humid air mass that forms over oceans |
| meteorologists | scientists who study and predict weather |
| occluded front | a warm air mass trapped between two cold air masses |
| precipitation | any and all forms of water, such as rain, snow, or hail, which falls from clouds and reaches the ground |
| stationary front | a cold air mass and a warm air mass that have collided but neither has the strength to move the other |
| storm | a violent disturbance in the atmosphere |
| storm surge | a dome of water that sweeps across the coast where a hurricane lands |
| tornado | a rapidly whirling, funnel shaped cloud that reaches down from a cloud to touch Earth's surface |
| tropical air mass | a warm air mass that forms in the tropics and has low air pressure |
| warm front | a moving warm air mass collides with a slowly moving cold air mass - because the movement is slow, the weather may be rainy or foggy for several days |
