Recently we would have heard the term “Low pressure area” in the news. We would have also heard about the term “Depression in the sea”. What does it mean?
We know about the occurrence of rain. We would have studied about it in our lower classes in the name of “Water cycle”. The heat energy from the sun makes the sea water to evaporate and form clouds. When these clouds hit the land, precipitation occurs in the form of rain, snow or hail. This gets collected in lakes or ponds or goes to the sea through rivers. This is how a tropical rain looks like. But what about the monsoon systems?
One of the main parts of a monsoon rain systems is a low pressure area or a depression. Low pressure area is an area in which the pressure is lower than its surrounding places. Air rises and blows in an anticlockwise direction around the low pressure area in the northern hemisphere while air rises and blows in an clockwise direction around the low pressure area in the southern hemisphere. As it rises and cools, water vapour condenses to form clouds and precipitation may occur.
But what is the relationship between this and a cyclone?
When warm and moist air over the sea rises away from the ocean surface, it creates the low pressure area. It causes the air from the surrounding areas with higher pressure to move towards the low pressure area which in turn leads to warming of the air and causes the air to rise again. The air rising and cooling leads to the formation of clouds. The system of clouds and wind spins and grows leading to the formation of a cyclone. The intensity of a cyclone reduces the moment its eye enters the land region.
Does the low pressure areas cause rains?
Yes it does!! As discussed before, low pressure areas do contain rain clouds. The intensity of rain due to a low pressure area will be more than the intensity of rain due to a cyclone. It’s because the low pressure area readily gets its water vapor from the sea meanwhile the cyclones move towards the land, causing the reduction in the intensity of rain. If the low pressure area is very weak, it won’t move anywhere else easily, causing more rains than a stronger low pressure area as its more likely to move away.
Mitigation and prediction of rain is as important as how rain is important to us. As too much of anything is good for nothing, too much of rain can cause floods and affects the everyday ,life of people. Proper mitigation and prediction of rain and the rain systems in the sea would help us take the necessary precautions.
Well, how to predict rain unprofessionally?
Notice the direction of wind. The direction of wind changes during the southwest monsoon season and the north east monsoon season.. The direction of the rainclouds depends on the direction of wind. When a new rain system/cycle is about to be formed, you can see Stratus clouds. You can also see this clouds during the end of a cycle. When it’s about to rain, you can see the nimbus clouds, along wait the water vapour clous moving fast towards the nimbus clouds. When the humidity is high, there’s a high possibility of rain.
So what are you waiting for? Put down your phone and Start predicting rain!!