| A | B |
| humidity | amount of water vapor in the air |
| capacity | the amount of material something can hold |
| absolute humidity | the actual amount of water vapor in the air |
| saturated | filled to capacity |
| relative humidity | amount of moisture in the air compared to its capacity |
| psychrometer | an instrument used to find relative himidity |
| condensation | changing from a gas to a liquid |
| dew | water that condenses on cold surfaces |
| dew point | temperature at which water vapor condenses |
| frost | ice that forms by condensation below the freezing point |
| cirrus clouds | light and feathery clouds |
| cumulus clouds | big and puffy clouds |
| stratus clouds | clouds that form a sheet across the sky |
| air mass | a large volume of air that covers a region |
| maritime | having to do with the sea |
| polar | having to do with the areas around the North and South Poles |
| tropical | having to do with the warm regions around the equator |
| front | surface between two air masses |
| stationary | not moving |
| stationary front | front that does not move |
| meteorologist | a weather scientist |
| station model | a record of weather information at a weather station |
| millibar | a unit of measurement for air pressure |
| isobar | line drawn on a weather map connecting points of equal air pressure |