Question 1

Question 8What are Trade Winds? How are they caused?

Accepted Answer

Trade Winds are the surface winds which move from the Horse Latitudes to the Doldrums. In the Northern Hemisphere, they are the North-East trades and in the Southern Hemisphere, the South-East trades.The wind always blow from high pressure area towards low pressure area. The trade winds are caused by movement of winds from Sub-Tropical high pressure belts towards equatorial low pressure belt.

Question 2

Question 13What are causes and consequences of shifting of pressure belts?

Accepted Answer

The causes of shifting of pressure belts are inclination of Earth's axis and change in relative position of Earth with Sun -At the time of Summer solstice the Sun is vertical over the Tropic of Cancer and therefore, all the pressure belts except the northern polar high pressure belt shift northward.After Autumn Equinox, there is southward migration of the Sun which becomes vertically over the Tropic of Capricorn at the time of Winter Solstice and therefore the pressure belt shifts southward except in the southern polar high pressure belt.The Sun is overhead over the Equator at the time of Spring Equinox and Autumn Equinox and hence all the pressure belts occupy their normal positions.The shifting of pressure belts has the following consequences:It influences the areas of Mediterranean climate and the position of Westerlies which move northward in the summer season (June) and southward in the winter (December) season.The summer and winter monsoons and the complete reversal of wind direction are also the results of shift of pressure belts.Both the trade and anti-trade winds are thus closely influenced by the shift of belts.

Question 3

Question 14What is Coriolis Force? What is its result?

Accepted Answer

If the earth did not rotate on its axis, winds would follow the direction of the pressure gradient. Instead, Earth's rotation produces a force which tends to turn the flow of air. This force is called the Coriolis Force. It results in the deflection of air towards the right in the Northern Hemisphere and toward the left in the Southern Hemisphere.

Question 4

Question 15What are Local Winds? Give examples.

Accepted Answer

Local winds are types of winds which blow for a short duration and affect the climate of the region where they blow. These winds originate in a specific region and blow over a limited area. Local winds are generally known by a common name throughout the world. Some examples of local winds are Loo, Mistral, Fohn, Chinook, Norwester, etc.

Question 5

Question 16What are Land and Sea breezes?

Accepted Answer

The Land Breeze is a diurnal wind blowing from the land out to sea. It is caused by the differential cooling of land and sea. The cooling of the air over the land by radiation during the night causes the air to descend and flow seawards. Therefore during the night there is low pressure over the heated sea and high pressure over land. Hence, winds blow from land to sea during night.The Sea Breeze develops along sea coasts or large inland water bodies in summer when the land heats much faster than the water on a clear day and a low pressure develops over the land. Under these conditions, in the day, the air blows from the sea to the land as there is high pressure on the sea and low pressure over the land.

Question 6

Question 17Explain a sea breeze with the help of a diagram.

Accepted Answer

The Sea Breeze develops along sea coasts or large inland water bodies in summer when the land heats much faster than the water on a clear day and a low pressure develops over the land. Under these conditions, in the day, the air blows from the sea to the land as there is high pressure on the sea and low pressure over the land. Below diagram explains the formation of sea breeze:

Question 7

Question 18What are Monsoon Winds? How are they caused?

Accepted Answer

Monsoon Winds are periodic winds like the sea and land breezes on a large scale. The monsoon is a seasonal wind which blows in a fixed direction during a particular season. It reverses its direction as the season changes. They are divided into two Wind Systems the Summer Monsoon and the Winter Monsoon.Theses winds develop due to differential heating of land and sea over a large area.

Question 8

Question 19In what way does the land and sea breeze affect the temperature of a place?

Accepted Answer

Land and sea breezes are local periodic winds on a diurnal basis. They develop due to differential heating of land and sea. These winds have a moderating effect on the temperature of the place. The temperature is neither too hot nor too cold. These winds also provide relief from the stagnant humid heat.

Question 9

Question 20What is a Cyclone? How is it caused?

Accepted Answer

Cyclones are strong winds which can blow at any place and time. These are the centres of low pressure which may last for a few days or few hours. Cyclone winds blow with great speed towards the centre which is the eye of the storm. The movement of wind is anticlockwise in northern hemisphere and clockwise in southern hemisphere.Cyclones are caused due to formation of low pressure area which becomes the centre of cyclone. The air from all directions rushes towards the low pressure area with great force in clockwise or anticlockwise direction.

Question 10

Question 21Describe the weather conditions associated with the cyclones.

Accepted Answer

Due to extreme heat, there is development of a strong low pressure area which initiates cyclones. They are generally associated with heavy rains, cloudy skies and stormy weather. After cyclones, the weather becomes pleasant.

Question 11

Question 22What are Anticyclones? How are they caused?

Accepted Answer

Anticyclone is a high pressure area. In the Northern Hemisphere, winds blow in a clockwise spiral away from the centre while in Southern Hemisphere, winds blow in an anti-clockwise spiral.Anticyclones are caused due to descending of warm air which is completely devoid of moisture.

Question 12

Question 23What are Tropical and Temperate Cyclones?

Accepted Answer

Tropical Cyclone — Tropical Cyclones start within 8° and 15° - 20° North and South of the Equator where surface-sea temperature reaches 27°C. The air above the warm sea is heated and rises up. This causes the low pressure. The weather system produces heat which increases the wind speed. These cause the tropical cyclones to sustain itself. These cyclones are associated with high temperature and high humidity.Temperate Cyclone — They are common near the sub-polar low pressure belts. The warm moist Westerlies from the South converse with the polar Easterlies from the north. The cold air mass is known as cold front and the warm air mass is known as warm front. When these fronts meet, it causes rainfall. Front is the zone of contact between the two. They are more frequent in winter·than in summer.

Question 13

Question 24What are Variable Winds?

Accepted Answer

Variable winds are those winds which blow in a small area and are related to the pressure systems. They are known as variable winds as they do not blow in a definite direction and their speed and velocity varies with the pressure system. Two main kinds of variable winds are cyclones and anti-cyclones.

Question 14

Question 25Name two special types of tropical cyclones and for each name the specific region where it is experienced.

Accepted Answer

Two special types of tropical cyclones are:Typhoons in South China Sea.Hurricanes in Caribbean Sea.

Question 15

Question 26Name an area where typhoons are experienced.

Accepted Answer

Typhoons are experienced in South China Sea.

Question 16

Question 27What are lsobars?

Accepted Answer

Isobars are imaginary lines drawn on a map to join places having same or equal mean atmospheric pressure reduced to a sea level.

Question 17

Question 28Name the factors affecting air pressure.

Accepted Answer

The factors affecting air pressure are:Altitude.Temperature.Earth rotation.

Question 18

Question 29How are Weather Maps important for us?

Accepted Answer

Weather maps consist of isobars to show atmospheric pressure because different pressure systems cause different types of weathers. The spacing of isobars indicate the pressure gradient. The closer the isobars, the steeper the gradient of pressure and the weather is stormy. When isobars are far apart from each other, there is a little difference in the atmospheric pressure. Therefore, weather maps are important in weather forecasting.

Question 19

Question 30List the main causes for development of local winds.

Accepted Answer

The main causes for development of local winds are:Unequal heating of land and sea resulting into land and sea breezes.Heating and cooling of the mountain slopes.Local winds originating because of the deformation of air currents, crossing of mountain ranges and physical barriers.Convectional Local Winds caused by steep pressure gradients and steep variations in local temperatures.

Question 20

Question 31What are Jet Streams?

Accepted Answer

Jet streams are fast flowing narrow air current found in the upper atmosphere or in troposphere of some planets including earth. The main jet streams are located near the altitude of the tropopause.

Atmospheric Pressure and Winds

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