As the earth is affected by an unequally
of heat energy from the sun, the state of the air differentiate between different regions.
Warm air expands and rises up while cold air condenses and sinks, hence resulting the flow of
air and forms wind. In meteorology, unless otherwise specified, wind means the horizontal motion
of airflow and signifies with wind direction and wind speed (wind force). Wind direction
indicates the direction from which the wind is blowing and is usually reported to one of the
16 points of the compass (N, NE, etc.) or 360° with reference to true north. Wind speed
indicates the rate of the motion of the air on a unit of time and is usually measured in meter
per second (m/s), kilometer per hour (km/h) or knots.
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