Wind And Storm

Front 1

Wind

Back 1

Wind is the movement of air in a horizontal direction in the atmosphere.

Front 2

What causes wind?

Back 2

It is caused by a difference in temperatures between different regions of the Earth. This occurs because of the uneven heating of the Earth's surface. Air expands upon heating. As warm air rises, cooler air takes its place & sets up a current of air called wind.

Front 3

Monsoon Winds

Back 3

During the summer, air over the land gets heated
& rises. Cool rain bearing wind from the ocean blow over the land. These winds are monsoon winds.

Front 4

Air Pressure

Back 4

The pressure exerted by air in the atmosphere is air pressure.

Front 5

Factors on which air pressure depends on

Back 5

Height of a place & Temperature:

Areas with lower temperature have higher pressure. Air moves from and area of higher pressure to lower pressure. This causes wind.

Front 6

Moving Air Provides a Lift

Back 6

Moving air provides a lift. When you blow on a strip of paper, the pressure on top of it is reduced. The pressure below the paper is greater than the pressure above it. This causes the paper to be pushed upwards. Therefore, moving air provides a lift.

Front 7

Characteristics of Wind

Back 7

Two important characteristics: direction & speed

Direction is measured with wind vane

Speed is measured with anemometer

Front 8

Wind Vane

Back 8

Also called a weather vane. It has two parts-the front & the rear. The front part has a smaller surface area than the rear. Common shapes for the wind vane are an arrow & a rooster. It is mounted onto a vertical column and moves when the wind blows. The arrow aligns with the direction of the wind.

Front 9

Anemometer

Back 9

In a cup anemometer, there are three to four cups mounted symmetrically at right angles to a vertical axis. The force exerted by the wind is greater on the inside than on the outside. This causes the cups to rotate. The rate of rotation is proportional to the wind speed.

Front 10

Storms

Back 10

Storms are severe atmospheric disturbances accompanied by strong winds. They set off when different type of air masses meet. Storms range from moderate to very severe.

Front 11

Different names of Storms

Back 11

Hurricanes- North America

Typhoons- East Asia

Cyclones- India

Front 12

Cyclones

Back 12

They develop over the oceans near the equator. The water heats up the atmosphere above it and warn air rises. Cool air rushes in to take its place. This results in many thunderstorms over the ocean, which merge into one big storm. Due to Earth's rotation, the winds spin. If they spin above 64 km/hr, it is a tropical storm. The center of the storm is called the eye of the storm.

Front 13

Damage caused by a cyclone

Back 13

Trees are uprooted and buildings are flattened. The cyclone comes with heavy rains. They come with high waves called storm surge and circulate counterclockwise in the Northern Hemisphere are clockwise in the Southern Hemisphere.

Front 14

Tornadoes

Back 14

It is a violent spinning storm shaped like a funnel with the narrow end on the ground. They develop from thunderstorms and are formed on land. Tornadoes are narrow unlike cyclones.

Front 15

Safety measures during a storm

Back 15

Remove materials that could be blown away easily. Stay indoors and secure windows. Do not stay in your car or under a tree. Avoid anything that touches electricity lines. People near coastlines should evacuate. Fishermen must not fish during a storm. Food, water, medicines, torch lights, and batteries should be kept at home.