Fast moving air towards a centre; usually with heavy rain; is known as cyclone. Wind direction, wind speed, humidity and temperature together create cyclone.
When water vapour in the clouds cools down it releases heat. This heat warms the air around the clouds. The warm air rises up and creates a low pressure zone. This low pressure zone is quickly filled in by cooler air from the surrounding. This creates a system in which the centre is having very low pressure and is surrounded by wind moving around it. The wind from the surroundings moves in a circular fashion towards the centre and gives rise to cyclone.
The centre of the cyclone is called ‘eye’. A cyclone may be 10 to 15 km high. It is a rotating mass of air. The diameter of eye may be vary from 10 to 30 km. Eye of a cyclone is a calm area, but around the eye air may move with high speed such as 150 to 250 km/h.
Destruction caused by Cyclone: A strong cyclone can be very destructive.
Since cyclone is accompanied with high speed wind, it can damage houses, telephone poles, electric poles and uproot trees.
Strong wind of the cyclone may push the sea water towards the sea shore in the form of high wave. These high waves may damage houses and push water to low land which may be accompanied with loss of life and properties.
Being the area of very low pressure, eye of cyclone lifts water in the centre. This may cause the rise of water up to 3 to 15 metre high. This appears like a water wall. This water wall; when pushed towards seashore; can inundate a large area, which can cause the loss of life and property.
In India, the eastern coastal region is more vulnerable to cyclones; in terms of intensity and frequency of cyclones, compared to the western coast.
Cyclone is known by different names in different countries. Cyclone is known as HURRICANE in the American continent. It is known as TYPHOON in Philippines and Japan.
TORNADOES: Tornadoes are the very fast moving dark cloud in the shape of a funnel. The speed of violent tornadoes may be up to 300km. Tornadoes are as destructive as cyclone. Tornadoes may form within cyclones.
ANEMOMETER: An instrument which measures the speed of wind.
Effective Safety Measures:
(1) Safety services towards cyclone and other disaster by Government and other agencies:
- Cyclone forecast and warning services: With the advances in technology, cyclone can be forecast in about 24 to 48 hours in advance. This becomes possible because of satellites and computers. When a cyclone is nearer to the coastline, the cyclone warning is forecasted almost at every half an hour.
- Rapid communication to the Government and concerned people: Communication about the cyclone is given quickly to the Government and the people so that proper safety measures and rescue operations can be carried out.
- Construction of cyclone shelters in the cyclone prone area.
- Shifting the people quickly to a safer place.
(2) Action on the part of people:
- Pay attention towards warning broadcasts from time to time.
- In case of a cyclone warning, stock necessary food items and medicines.
- If possible, move to a safer place.
- Fishermen should not venture into the sea during a cyclone warning.
- Cooperate with others in the community.
- Help the rescue team.
- Moving air is called wind.
- Air exerts pressure.
- Air expands on heating.
- Warm air is lighter and rises up.
- Air moves from high pressure to low pressure.
- Air Current: Movement of air from high pressure zone to low pressure zone creates air current.
- Uneven heating on land creates air current.
- Air moves from 0-30⁰ north and from 0-30⁰ south towards equator.
- Land gets heated as well as loses heat faster than water.
- Monsoon: The flow of air from ocean towards land in summer is called Monsoon or Monsoon wind.
- Monsoon winds carry vapour which falls over the land in the form of rain after cooling down.
- In India harvest is depend on monsoon wind, which brings rain.
- Thunderstorm: Rain with lightning is called thunderstorm. This happens mostly in the summer.
- Thunderstorm occurs frequently in hot and humid tropical areas, such as India.
- Cyclone: Fast moving air towards a circle usually with heavy rain is known as cyclone.
- Wind direction, wind speed, humidity and temperature together creates cyclone.
- Eye: Centre of cyclone is known as eye.
- Tornadoes: Tornadoes are the very fast moving dark cloud in the shape of funnel. Tornadoes may form within cyclones.
- The speed of violent tornadoes may be up to 300km.
- Tornadoes are as destructive as cyclone.
- Anemometer: An instrument which measures the speed of wind.