Social Science VSQ (2 Marks)

Sun rays falls almost vertically on the equator and covers less space whereas sun rays falls at slanting angle on the poles and covers more space. Thus, the amount of insolation decreases from the equator towards the poles.

Weather is short-term state of the atmosphere whether it is hot or cold, wet or dry. It is the hour to hour, day to day condition of the atmosphere.

The sum total of all weather conditions prevailing over large area for a longer period of time is called climate.

Astronauts wear a protective suit filled with air when they go to moon because the counter pressure exerted by the body would make the blood vessels burst.

Plants need nitrogen for their survival. They cannot take nitrogen directly from the air. Bacteria that live in the soil and roots of some plants take nitrogen from the air and change its form so that plants can use it.

Air above us presses us with a great force on our bodies. However, we don’t even feel it. This is because the air presses us from all directions and our body exerts a counter pressure.

When air is heated, it expands, becomes lighter and goes up. Cold air is denser and heavy. That is why it tends to sink down. When hot air rises, cold air from surrounding area rushes there to fill in the gap. That is how air circulation takes place.

When trees on hill sides are cut, rainwater flows down the bare mountains. This causes flooding of low lying areas.

When water evaporates from different water bodies and land it turns into water vapours or moisture. Moisture in air at any time is known as humidity.

1. Rain
2. Snow
3. Sleet
4. Hail

Astronauts have to wear special protective space suits filled with air when they go to the moon. If they did not wear these space suits, the counter pressure exerted by the body of the astronauts would make the blood vessels burst. The astronauts would bleed.

The temperature in cities is much higher than that of villages because the concrete and metals in the buildings and the tar and asphalt in the roads gets heated throughout the day and absorbs heat. This heat is released at night hence there is the difference in the temperature.
The crowded high rise buildings trap the warm air and thus raise the temperature of the cities.

Jet planes flying in the sky leave a white trail behind them. The moisture from their engines condenses. We see trails of this condensed moisture for some time when there is no air movement to disturb it.

A powerful and destructive storm with very high speed winds that moving in circular motion around an area of low pressure.

Plants need nitrogen for their survival. They cannot take Bacteria. That live in the soil and roots of some plants, take nitrogen from the air and changes its form so that plants can use it.

Thermometer– measures temperature.
Barometer– measures atmospheric pressure.
Rain gauge– measures amount of rainfall.
Wind wane– shows direction of wind.

Weather is hour-hour conditions of atmosphere like hot humid weather may make us irritable but same day breezy or pleasant evening may make one cheerful. We have hot or cold climate over a period of few months.
Therefore we have daily forecast of weather and long term predictions of climatic conditions

This term refers to degree of moisture present in the air. There is a definite limit to the quantity of moisture that can be held by the air at a specific temperature.

Two gases such as carbon dioxide and ozone influence the atmosphere to a large extent.Their percentage in the atmosphere is as under:

• Carbon dioxide 0.03%
• Ozone 0.00006%

Maximum temperature is the highest temperature of the day recorded about 2:00 PM.

A day when air is full of water vapour is called a humid day. With the air getting warmer its capacity to hold moisture increases so it becomes more humid. On such days clothes takes longer to dry and even body sweat does not evaporate easily.

All living beings on this earth depend on the atmosphere for their survival. It provides us the air we breathe and protects us from the harmful effects of the sun’s rays. Without this blanket of protection, we would be baked alive by the heat of the sun during day and get frozen during night. So it is this mass of air that has made the temperature on the earth liveable.

Air pressure is the pressure exerted by the weight of air on the earth's surface. As we move in the upper layers of atmosphere, the pressure falls rapidly.

Precipitation in liquid form is called rain. Most of the ground water comes from rainwater. It is important for survival of plants and animals. It brings fresh water to earth.
If rainfall is more or trees are cut on hills, rain water can cause flooding in low lying areas. If it is less than water scarcity or drought may occur.

Carbon dioxide released in the atmosphere creates a greenhouse effect by trapping the heat radiated from the earth. It is therefore called a greenhouse gas and without it the earth would have been too cold to live in.

Based on the mechanism rainfall can be of three types: Convectional, Orographic or Cyclonic.

In cities we find high rise buildings. The concrete and metals in these buildings and the asaphalt of roads get heated up during the day. This heat is released during the night.
Another reason is that the crowded high rise buildings of the cities trap the warm air and thus raise the temperature of the cities.

The ionosphere or the thermosphere protects us from meteors and obsolete satellite from outer space.

The movement of air from high pressure to low pressure areas is called wind. For example wind blows dry leaves or strong wind uproots trees. Blowing smoke or dust is the work of wind. Strong wind makes it difficult to walk or hold umbrella.

Carbon dioxide in the atmosphere traps the heat radiated from the earth creating a green house effect. This makes the temperatures livable. Without this earth would have been too cold to live. But the increased emissions from vehicles and factories increases the temperature leading to global warming.

Nitrogen is the most plentiful gas in the air.

• Plants need nitrogen for their survival. They cannot take nitrogen directly from the air.
• Bacteria in the soil or the roots fix nitrogen by changing its form so that plants can use it.

Temperature is measured with the help of thermometer .Outdoor temperature is measured with the help of mercury thermometer.

Oxygen is the second most plentiful gas in the atmosphere. Humans and animals use it for breathing. Green plants produce oxygen through photosynthesis and thus oxygen balance is maintained in air. This gets disturbed if we cut trees.

• Convection Rainfall.
• Relief (Orographic) Rainfall.
• Convection Rainfall.

1. Green plants use carbon dioxide to make their food and release oxygen.
2. Humans or animals release carbon dioxide.
3. The amount of carbon dioxide released by humans or animals seems to be equal to the amount used by the plants which make a perfect balance.
4. However, the balance is upset by burning of fuels, like coal and oil. All this affects earth’s weather and climate.

Exosphere:

• The uppermost layer of the atmosphere is known as exosphere.
• This layer has very thin air.
• Light gases like helium and hydrogen float into the space from here.

Mesosphere:

• Mesosphere is the third layer of the atmosphere.
• It lies above the stratosphere.
• It extends up to a height of 80km.
• Meteorites bum up in this layer on entering from the space.

Importance of stratosphere:

1. Above the troposphere lies the stratosphere. It extends up to a height of 50km. This layer is almost free from clouds and associated weather phenomenon, making conditions most ideal for flying aeroplanes.
2. One important feature of stratosphere is that it contains a layer of ozone gas which protects us from the harmful effect of the sun rays.

Structure of the Atmosphere:The atmosphere is divided into five layers according to height, starting from the earth's surface.

• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
• Exosphere

Variation in Distribution of Pressure:

• As we go up the layers of atmosphere, the pressure falls rapidly.
• The air pressure is highest at sea level
• It decreases with increase in height.
• Horizontally the distribution of air pressure is influenced by temperature of air at a given place.

All living beings depend on the atmosphere for their survival:

• Atmosphere provides them the air they breathe.
• It protects them from the harmful effects of the sun's rays.
• Without its protection, they would be baked alive by the heat of the sun during day and get frozen during night.

1. Permanent winds.
2. Seasonal winds.
3. Local winds.

Among the four major elements of environment, the atmosphere is most dynamic as changes take place in it not only from one season to another but also over shorter periods of few hours.

The different layer of atmosphere are: troposphere, stratosphere, mesosphere, thermosphere, exosphere.

The air above us presses us from all sides with great force but we do not feel it. This happens because our body exerts a counter pressure.

Most of the ground water comes from rainwater. Plants help preserve water. When trees on hill sides are cut, rainwater flows down the bare mountains and can cause flooding of low lying areas.

The total amount of water vapour that is contained in the air at a given temperature is known as absolute humidity.

Insolation is the incoming solar energy intercepted by the earth. The amount of insolation decreases from the equator towards poles.