Water Vapour and Air Pressure
In atmosphere there always exists some water vapour. Through evaporation process enough water are evaporated from canals, ponds, water reservoir, rivers, oceans etc and mixes with atmosphere. From cloud, rain, fog, dew etc natural phenomena it is proved that there is enough water vapour in air.
In different places amount of water vapour in atmosphere is different. Again in some days water vapour remain more and in other days water vapour remains less. Then question arises, “On what factors does the presence of water vapour depend?” In its answer we can definitely say-
Amount of water vapour in atmosphere depends on the sources of water, latitude, location of the place above the sea level etc.
Importance of the presence of water vapour in the weather of a place is immense and unlimited. For proper growth and storage of materials presence of water in atmosphere and temperature at a place are needed to keep within a fixed limit. For this reason, importance for the determination of water vapour in atmosphere is very important. Water vapour pressure at a plate is dependent on the amount of water vapour. As the amount of water vapour increases more and more pressure also increases accordingly.
The effect of water vapor is evident within an air mass. Parcels of air that contain water vapor within a drier air mass are more buoyant and tend to have less air pressure and tend to rise. You can see evidence of this on a sunny day by looking at the scattered cumulus clouds. These clouds are a result of a parcel of air that are moister (contain more water vapor) than the surrounding air. They rise, and when they reach a certain cooling temperature, the water vapor in the column of rising air condenses into the clouds you see.
Vapours emitted from a liquid assert pressure, like ordinary gases, on the surface of the container. This pressure is the vapour pressure. This vapour pressure and water vapour influence our daily life.