Tornadoes — lesson. Science CBSE, Class 7.

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எங்கள் ஆசிரியர்களுடன் 1-ஆன்-1 ஆலோசனை நேரத்தைப் பெறுங்கள். டாப்பர் ஆவதற்கு நாங்கள் பயிற்சி அளிப்போம்

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In general, the Indian coastline is vulnerable to cyclones. But comparing to the east coast of India, the west coast is less vulnerable to cyclonic storms. The intensity and frequency of the cyclones in the east coast are more than on the west coast.

Cyclone in the Bay of Bengal

Destructions caused by cyclones:

Cyclones are very destructive in nature and can cause loss of lives in coastal areas.

Example:

On \(18\) \(October\) \(1999\), Orissa was hit by a cyclone at a speed of \(200\) \(km/h\). This cyclone has destroyed around \(45,000\) houses and made \(7,00,000\) people homeless. Again, a second cyclone with a wind speed of \(260\) \(km/h\) hit Orissa on \(29\) \(October\) in the same year, with water waves at the height of about \(9\ m\). Thousands of people lost their lives and property due to this cyclone. It also affected agriculture, transport, communication, and electricity supply.

Orissa hit by a cyclone

An approaching cyclone can be identified when they are hundreds of kilometres away from the shore. It is first indicated when the water is pushed towards the shore by a strong wind. The waves of the water will be so strong in nature such that a person cannot withstand them.

Cyclone in the coastal area

The water in the ocean is lifted by the low pressure in the eye of the cyclone. The height of the rising water can be \(3\)\(–\)\(12\) \(metres\) such that it looks like a wall of water moving towards the shore entering the low-lying coastal areas.

Ludington_Lighthouse_hit_by_a_wave_(8741875060).jpg

Violent waves hitting the light house

The fast blowing winds during the cyclone can cause damage to houses, trees, communication systems, etc. The cyclone causes a tremendous loss of life and property.

Destruction caused by a cyclone

The fertility of the soil is also affected by continuous heavy rainfall as the nutrients get washed away. This may even worsen the situation and can lead to floods.

Flood in a city

Storms and cyclones are worldwide phenomena. They are given different names in different parts of the world. In America, they is called ‘hurricanes’, whereas in the Philippines and Japan, they are called ‘typhoons’.

Tornadoes:

Tornadoes are common in the American continent, but in India, it is not very frequent.

A tornado is a violent, narrow, spinning storm that reaches from the sky to the ground. It is in the form of a dark funnel-shaped cloud. Mostly tornadoes are weak in nature.

A tornado

The speed of a violent tornado can travel at \(300\) \(km/h\). A tornado can be formed within a cyclone.

Schematic representation of a tornado

The diameter of a tornado can be of any size, ranging from \(metre\) to \(kilometre\). Due to the low pressure, the dust and the debris are sucked by the funnel of the tornado. It is then thrown out near the top of the tornado.

Tornado shelter:

A tornado shelter is a room without any windows situated underground.

A tornado shelter

Preventive measures during tornadoes:

In the time of tornadoes, one should shut the doors and windows and shelter under a table or a workbench to avoid debris from reaching them.
One can protect their head and neck using the arms and bowing down on their knees.