It is necessary to measure air pressure because it gives an idea about the amount of gases dissolve in water, the density of air at a particular place,the direction of winds etc.
Explanation:
The pressure exerted by the total volume of air in the Earth's surface is called air pressure. It is also called barometric pressure.
The air pressure decreases with decrease in air density and increases with increase in air density.
With increase in air pressure more oxygen is dissolved in water.
The direction of winds on Earth is also determined by the pressure belts. The winds move from region of high pressure to low pressure. Thus, measurement of air pressure helps in weather forecast.
