WINDS ,STORMS AND CYCLONES FULL QUESTION ANSWERS | MY EUREKA PLUS CHAPTER 8

II. 1. What is atmospheric pressure ?

Ans:  The column of air above a place exerts pressure and is known as atmospheric pressure .

2. What is humid air?

Ans:  Air which contains plenty of water vapour is called humid air .

3. What is wind?

Ans:  Moving air is called wind.

4. When does a region have clear weather ?

Ans:  Regions with relatively high air pressure usually experiences clear cum  weather .

5. What kind of weather will  a low pressure area normally have?

Ans:  A low pressure area will normally have cloudy , windy and stormy weather .

6. What are tornadoes?

Ans:  Tornadoes are  violently rotating columns of air .

7. Who issues cyclone alert in India?

Ans:  The Indian Meteorological Department (IMD) issues cyclone alert in India.

III. 1. How does altitude affect air temperature ?

Ans:  Altitude is the height of place above sea level and it affects air temperature . The higher the altitude the cooler is the place .

2. What causes coastal winds ?

Ans:  Flowing of wind  from a region of higher pressure to  lower pressure  causes coastal winds.

3. What are the conditions required to form cyclones ?

Ans:   Constant supply of warm and humid  air are the conditions required to form a cyclone.

4. When is a cyclone called hurricane ?

Ans:  A cyclone is called a hurricane when it rotates in an anticlockwise direction .

5. Why does a cyclone die down after it moves in land ?

Ans :  When the cyclone reaches the land the supply of warm ,humid air gradually stops as a result of which the cyclone dies down.

IV. 1. Why does a warm region have a low air pressure ?

Ans:  Warm region experiences low air pressure because when the surface of land or water warms up the air  above it also becomes warm a s a result of which the molecules of gases present  in the air moves further apart and air expands .

2. Why does low pressure  air spiral upwards?

Ans:  As the wind flows in opposite direction air spirals inward at the earth’s surface and continues to move upward.

3. Why does cooling of an area cause high pressure in the region ?

Ans:  When a surface of land or water cools ,the layer of air close to the surface also cools and the molecules of gases present in the air comes closer . As a result the layer of air  shrinks and the air from the upper region moves downward. Now the added mass of the extra air exerts high pressure at  the surface . Cold  air is also denser and exerts high pressure as a result of which cooling of an area causes high pressure in the region.

4. During the day breeze blows from the sea towards the sea coast . Explain with help of diagram .

Ans:  During the day sea water is cooler and the air above it is denser . Therefore the pressure over the sea is relatively high during the day as compared to the land. Now , as wind flows from a region of higher pressure to lower pressure during the day, wind blows  from the sea towards the land .

5. How  are cyclones formed?

6. What safety measures will you take in case of a cyclone alert  ?

Ans:  The safety measures to be taken in case of a cyclone alert are as follows – 

i) Keeping a first aid kit ready.

ii) Staying away from doors and windows.

iii) Turning off power , gas and water .

iv) Remaining indoors.

v) Staying tuned to radio/TV for further information .

vi) By not spreading rumours.