The air moves in currents over the earth's surface. The geography of your area will determine the winds. For example, prevailing winds are those that blow consistently in a particular direction. An anemometer is used to measure wind speed. Read more about wind and measuring the wind .
Air pressure is the weight of the air pressing against the surface of the earth.
It changes from day to day. As the elevation increases, the air pressure decreases. A barometer is used to measure air pressure. Read more about air pressure and air pressure measurement . Relative humidity is the amount of water in the air compared to the amount of water that the air can hold.