Tropical Cyclone

In the last post we discussed about how to observe the cyclone using satellite and radar products. In this post, we will discuss some interesting facts about the tropical cyclone.

When we think about the cyclone we think it as a whirling clouds in motion. Yes, cyclone is is a rotating air column around a low pressure area.

The least we know is that the cyclones rotates in anticlockwise in the northern hemisphere and clockwise in the southern hemisphere due to the rotation of the earth (Coriolis force). See Fig.1.

Fig. 1. Tropical cyclone in the Northern and Southern hemisphere

Source: scijinks.gov

One common question, we normally have is whether the Tropical cyclones and the Hurricanes are same or different? right.... They both are same but they have a variety of names like our original name and pet names. The tropical cyclones are known as Hurricanes in North America and Caribbean, Typhoons in western North Pacific, Willy-Willies in Australia, Baguio in Philippine Islands, Taifu in Japan and Cyclones in Indian Ocean.

All the cyclones when formed, they give a particular name these days like naming a child. So, we can identify them easily and the naming of cyclones is done by respective cyclone warning centers.

Fig.2. Tropical cyclone region Source: https://scijinks.gov/hurricane/

In the above image (Fig. 2) the tropical cyclone region is given. If you keenly observe the image you might note that there is no cyclone near the equator. This again because of the Coriolis force. For a cyclone to form there should be some starting point like preexisting rotation and that rotation is absent near the equator.

Similarly, you can note that all tropical cyclones are formed over the ocean. The reason is for a cyclone to form they need ample of warm, moist air that is abundant over tropical oceans that act as fuel for the cyclone like petrol for our cars. Possibility of cyclone formation over the ocean is when the temperature is 26.5 deg C from the top to 60-70 m depth in the ocean.

Another thing, in the formation of the cyclone is that there should not be much change in direction and wind speed in height in the atmosphere (weak vertical wind shear). This vertical wind shear is strong means cyclones will become weak.

After landfall, a cyclone become weak as the fuel source (warm, moist air) is cutoff over land.

Hope you now know some unknown facts about the tropical cyclones.

Stay tuned!