Tag: monsoon phenomena and its mechanism

When high speed wind blows from high pressure towards the low pressure centre is known as cyclone. Their frequency, direction and intensity varies from place to place. In terms of direction it blows clock wise in southern hemisphere and anti-cyclone wise in  northern hemisphere. The frequncy and intensity also varies with its location and depending on that cyclones are known in different names in different places.

An anti-cyclone originates when a mass of air with high pressure is encircled by that with low pressure. When such condition occurred the relatively cool and dry wind from high pressure blows out to the surrounding low pressure.  While blows out, the wind turns round and round. In anti-cyclone  there exits high pressure at the center, it is called the center or eye of anti-cyclone.

In the absence of rotation, the wind tends to blow from areas of high pressure to areas of low pressure. The stronger the pressure differences between a high-pressure system and a low-pressure system, the stronger the wind. The coriolis force caused by Earth's rotation gives winds within high-pressure systems their clockwise circulation in the northern hemisphere as the wind moves outward and is deflected right from the center of high pressure and anticlockwise circulation in the southern hemisphere as the wind moves outward and is deflected left from the center of high pressure. Friction with land slows down the wind flowing out of high-pressure systems and causes wind to flow more outward from the center.

Western disturbances, specifically the ones in winter, bring moderate to heavy rain in low-lying areas and heavy snow to mountainous areas of the Indian Subcontinent. They are the cause of most winter and pre-monsoon season rainfall across northwest India.

The eye is a region of mostly calm weather at the center of strong tropical cyclones. The eye of a storm is a roughly circular area, typically 30–65 km (20–40 miles) in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the most severe weather occurs.