World Geography / Climatology
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Cyclone is an intense form of weather disturbance. It is a narrow intense low pressure zone surrounded by high pressure zone. There are two types of cyclones that occur in the world namely, Tropical cyclones and Temperate cyclones. In cyclones, winds converge into a low pressure zone added by Coriolis force and hence become spiraling or gyratory in nature. That is why, we will see very heavy rainfall of higher intensity accompanied by lightning and thunder in cyclones. These strong spiraling winds are referred to as Gales and their speed may reach up to 200 kmph.
The main cause of cyclone formation is due to the rising of warm air over the sea or ocean surface in a low pressure area. As the warm air rises upwards, the surrounding cool winds rush towards the warm air due to the pressure difference. As the cool air heats up, it again rises in the atmosphere. This process continues and an eye-like structure is formed at the center. The surrounding low pressure area around the eye continuously gets filled with high pressure winds to make it a cyclone.
There are mainly two types of cyclones, Tropical cyclones and Temperate cyclones. The approach of a Cyclone can be recognized if we observe (i) a sudden and steep rise in temperature of surface area, (ii) sudden and abnormal decrease in pressure, (iii) sudden change in the wind direction (like W to E becomes E to W) and (iv) change in the cloud structure.
These two types of cyclones occur in the lower Troposphere i.e. up to 5-7km. In upper layer of the Troposphere and in the Stratosphere, the weather is stable, calm and quiet. There are slow and shifting winds here. They blow from West to East, which are called Upper Air Westerlies. There is no moisture here.
Clouds can be of different types depending on the Altitude and the Structure
There can all combinations clouds like Cirrostratus, Nimbostratus, Cumulonimbus, etc. The increasing order of intensity of clouds is Cirrus, Cirrocumulous, Nimbus, Nimbostratus and finally Cumulonimbus.
These are vertically hanging clouds. They are extremely dark in colour (dark grey or dark black). They are having devilish and frightening appearance. These are associated with highest turbulent weather conditions. Different types of Cyclones are associated with Cumulonimbus clouds and will be having cloud bursts, thundering and lightning.