| A | B |
|---|
| Weather | the state of the atmosphere at a given time or place |
| Air pressure | force of air against a unit of area |
| Barometer | instrument used to measure air pressure |
| humidity | amount of water vapor in the air |
| relative humidity | amount of water vapor in the air compared to the maximum amount of water vapor the air can hold |
| Psychrometer | instrument used to measure relative humidity |
| Anemometer | instrument used to measure wind speed |
| wind vane | instrument used to find wind direction |
| rain gauge | instrument used to measure the amount of rainfall |
| air mass | large section of the atmosphere with the same temperature and humidity throughout |
| front | moving boundary line between two air masses |
| warm front | boundary ahead of a warm air mass that is pushing out and riding over a cold air mass |
| cold front | boundary ahead of a cold air mass that is pushing out and wedging under a warm air mass |
| high | cold area of high air pressure |
| low | warm area of low air pressure |
| isobar | line on a weather map connecting areas of equal air pressure |
| tornado | powerful wind storm with a whirling, funnel-shaped cloud and extremely low pressure |
| hurricane | severe tropical storm with high winds that revolve around an eye |
