2.  The present state of the atmosphere.

3.  The amount of water vapor held in the air.

4.  A measure of the amount of water vapor that air is holding compared to the amount it can hold at different temperatures.

5.  The temperature at which air is saturated and condensation forms.

6.  Clouds form due to warm air being forced upward, expanding, and cooling.  There are 3 basic types.

7.  Clouds that form layers or smooth sheets in the sky.  They form at low altitudes. (fog)

8.  Clouds that are large and white, often with flat bases.  These are known to produce fair weather or thunderstorms

9.  High, thin, white, feathery clouds containing ice crystals.  Fair weather clouds but can indicate approaching storms.

10.  A large body of air that has the same properties as Earth’s surface.

11.  Masses of air molecules pushing down from above.

12.  The boundary between cold and warm air masses.

13.  Sends out repeated radio waves and monitors the reflected waves from distant storms.  Helps predict weather.

14.  A violent, whirling wind that moves in a narrow path over land.

15.  A large, swirling, low-pressure system that forms over tropical oceans.

16.  A person who studies weather.

17.  Instrument used to measure air pressure.

18.  Measures the amount of wind that is present.

19.  Used to measure wind speed.

20.  Measures wind direction

21.  Measures the amount of rainfall