a short note on pressure and wind
Answers
Air in horizontal motion is Wind, And Atmospheric Pressure determines the rise and sink of air. The pressure and winds in atmosphere determine formation of air masses and occurrence of storms.
Atmospheric pressure – Weight of air column contained in a unit area from mean sea level to the top of atmosphere is known as Atmospheric pressure. It is measured in force per unit area. It is expressed in ‘milibar’/mb unit. For practical purposes, the atmospheric pressure is expressed in kilo-pascals.
Due to gravity, air at surface is denser and has higher air pressure. It is measured by the mercury barometer or aneroid barometer.In lower atmosphere, pressure decreases rapidly with height. At sea level, average atmospheric pressure is 1,013.2 milibar.
Wind – When air moves from high pressure areas to low pressure areas.
Vertical pressure gradient force is much larger than the horizontal pressure gradient. But we don’t feel strong upward winds because vertical gradient is balanced by gravitational force. Horizontal distribution of pressure is studied by drawing isobars at constant levels.
”shadow” align=”aligncenter”Isobars are lines connecting places having equal pressure. To eliminate effect of attitude on pressure, it is measured at any station after reducing to sea level for purposes of comparison. Low pressure system is enclosed by one or more isobars with lowest pressure at centre. High pressure system is also enclosed by one or more isobars with highest pressure in centre.