Winds Storms and Oceans

Start music Jan 4 2017 || 11:14 PM

Air & Wind

Air Pressure

The pressure exerted by the atmosphere
Air moves from the region of higher air pressure to a region of lower air pressure
When warm air rises at a place, the air pressure is lowered
Cold air from the surroundings rush in to occupy the space vacated by warm air
This promotes convection of air

Wind Speed and Air Pressure

Generation of wind currents on earth

Uneven heating between the equator and the poles

As the warm air rises near the equator, and the cooler air from the regions in the 0–30 degrees latitude belt on either side of the equator moves in
These winds blow from the north and the south towards the equator
At the poles, the air is colder than that at latitudes about 60 degrees.
The warm air at these latitudes rises up and the cold wind from the Polar Regions rushes in, to take its place
In this way, wind circulation is set up from the poles to the warmer latitudes
In reality, the winds don’t flow in the north-south or south-north direction as we expect. It changes in direction as shown below
This change in direction is caused by the rotation of the earth

Uneven heating of land and water

Thunderstorms

Thunderstorms develop in hot, humid tropical areas
The rising temperatures produce strong upward rising winds.
These winds carry water droplets upwards, where they freeze, and fall down again.
The swift movement of the falling water droplets along with the rising air create lightning and sound.
It is this event that we call a thunderstorm

Thunderstorm à cyclone

Before cloud formation, water takes up heat from the atmosphere to change into vapour.
High up in the air, water vapour then changes back to liquid (as raindrops),
When it does that, the heat is released to the atmosphere.
The heat so released, warms the air around.
The air tends to rise and causes a drop in pressure.
More air rushes to the centre of the storm.
This cycle is repeated.
This leads to the formation of a very low-pressure system with very high-speed winds revolving around it, called cyclone. (figure below)

Factors contributing to the formation of cyclones

Destruction Caused by Cyclones

The low pressure in the eye lifts water surface in the centre.
The rising water may be as high as 3–12 metres
As a result, the seawater enters the low-lying coastal areas
Apart from causing loss of life and property, it also reduces the fertility of the soil
High-speed winds accompanying a cyclone can damage telephones and other communication systems, uproot trees and impairs the infrastructure of the region
The entire east coast of India is vulnerable to cyclones than the west coast

Different names of cyclones

Tornado

A dark funnel shaped cloud that reaches from the sky to the ground
Most of the tornadoes are weak but strong ones might travel at a speed of 300 kmph
Tornadoes may form within cyclones.
In India, tornado is not very frequent

Safety measures

By the government

A Cyclone alert or Cyclone watch is issued 48 hours in advance of any expected storm
A Cyclone warning is issued 24 hrs in advance
Rapid communication of warnings and safety precautions to the Government agencies, the ports, fishermen, ships and to the general public
Construction of cyclone shelters in the cyclone prone areas,
Administrative arrangements for moving people fast to safer places

By the people

Make necessary arrangements to shift the essential household goods, domestic animals and vehicles, etc. to safer places
Keep ready the phone numbers of all emergency services
Should not ignore the warnings issued by the meteorological department
Avoid driving on roads through standing water

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