| A | B |
|---|
| Air mass | a large body of air that has properties similar to the part of the Earth over which it forms. |
| Anemometer | a weather instrument used to measure wind speed in miles per hour. |
| Barometer | a weather instrument used to measure air pressure in inches of mercury or millibars (mb). |
| Front | a boundary between two air masses of different temperature, moisture, or density. |
| Humidity | the amount of water vapor (moisture) in the air. |
| Hygrometer | a weather instrument that uses internal circuitry or devices to determine relative humidity. |
| Isobar | a line of constant pressure on a weather map. |
| Isotherm | a line of constant temperature on a weather map. |
| Relative humidity | the amount of water vapor in the air as a percentage of the maximum amount of water vapor the air could hold at that temperature. |
| Meteorologist | a person who studies day-to-day weather. |
| Sling psychrometer | a weather instrument that consists of a wet-bulb and a dry-bulb thermometer used to measure relative humidity. |
| Thermometer | an instrument used to measure temperature in degrees C or F. |
| Weather | the condition of Earth’s atmosphere at any given time. |
| Wind vane | a weather instrument used to measure wind direction. |
