Download 3.unit-4 (Geo)Learning partnership CW Answer key

DELHI PUBLIC SCHOOL TAPI
VII LEARNING PARTNERSHIP Geography HW 4
Answer Key
1. Writing Task: Write the short note on composition of air with the help of
diagram (5 marks) (Refer textbook )
 Air is not a single gas. It is a mixture of many gases, water vapor and other
particulate matter.
 The actual composition of air varies from place to place.
 Nitrogen and Oxygen are two masses which make up of the most of the
atmosphere
 Carbondioxide , helium , ozone , argon and hydrogen are found in lesser
quantities.
 Besides tiny dust particles are also present in the air .The pie char above gives up
the percentage of different constituents of air.
[Time: 20 minutes
MI: Verbal; Logical; Intrapersonal
RBT: Understanding]
2. Writing Task: : Answer the following questions in your Geography notebook
1 What is global warming?(1)
Ans: The heat retained increases the temperature of the atmosphere . It is called global
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warming.
Q 2 Apart from nitrogen and oxygen, what other gases are found in the air in small
volume? Mark (1)
Ans: carbon dioxide, helim ozone , hydrogen
Q 3 What is atmosphere?(1)
Ans: The envelope of air surrounding the earth is called atmosphere.
II. Match the following
A) Troposphere i)0-13
B) Stratosphere ii) 13-50
C)Mesosphere
iii)50-80
D)Thermosphere iv) 80-400 km
[Time: 20 minutes
MI: Verbal
RBT: Application]
4.Visual and Writing Task : Watch the following video and answer the following
questions
https://www.youtube.com/watch?v=Lisc4Xgh4ow
Read Lesson 4 and answer the following questions:
1. Define air pressure . How does air pressure vary from equator to poles and from
surface to heights.
 Ans: Air above us presses us with a great force
 But we do not feel it.
 This it because of the air presses us from all directions and our body
exerts a counter pressure.
 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.
 This creates a low pressure area
 Low pressure is associated with cloudy skies and wet weather.
2. Define low and high pressure.
Ans:
 In areas where temperature is high the air gets heated and rises. This
creates a low pressure area.
 n the area having low temperature the air is cold. It is therefore heavy.
Heavy air sinks and creates a high pressure
[Time: 20 minutes
MI: Verbal
RBT: Application]
5.Visual and Writing Task: Watch the video given below these questions and
answer the questions based on this video
https://www.youtube.com/watch?v=UKpLTHqU94o
a. Give a brief description about the different types of wind with the help of
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diagram.(5 marks)
a.Permanent winds-
The winds blowing almost in the same direction throughout the year are called
permanent or planetary winds. Trade winds, Westerlies and Polar winds are
included under it.
Trade winds : Hence, trade winds are the winds having fixed paths..
Westerlies : These are the permanent winds blowing from the sub-tropical high
pressure, belts to the sub-polar low pressure belts in both hemispheres. The
general direction of Westelies is South West to North East in the N..
Polar winds: Winds blowing from the high-pressure belts to the sub-polar low
belts, in both the hemispheres, are called polar winds.
b. Periodic winds- Winds which blow periodically from different directions
i.e. Monsoon winds, valley and mountain winds. Sea breezes
c.Local winds-Winds which blow during a particular period in a small area.For
example Foehn in Switzerland ,Chinook in USA and loo
b. Give a brief description about different types of rainfall(5 marks)
click on the link to know more
https://www.quora.com/What-are-the-different-types-of-rainfall
Convection rainfall
 when the sun heats a water source to the point that water turns into vapor and
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rises.
 By the time it reaches the condensation level, the vapor is usually cool enough to
turn back into water and fall in the form of rain
Orographic(Relief) rainfall
1 The prevailing winds pick up moisture from the sea as they travel across it, making
the air moist.
2 The moist air reaches the coast and is forced to rise over mountains and hills.
3 This forces the air to cool and condense, forming clouds.
4 The air continues to be forced over the mountains and so it drops its moisture as relief
rain.
Once over the top of the mountain the air will usually drop down the other side,
warming as it does so. This means it has a greater ability to carry water moisture and so
there is little rain on the far side of the mountain. This area is called the rain shadow.
Cyclonic rainfall.
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



This type of rain usually is due to the occurrence of cyclonic activities
It happens due to the meeting of hot and cold air masses.
The warm air slowly rises over the heavier cold air.
Thus the cold, dry air comes in contact with the warmer, moist air by which the
warm air cools and form clouds leading to rainfall.
 This type of rain pours down steadily for a few hours to a couple of days.
(a)Writing Task : Read Lesson 4, and Explain the following terms: (2 marks)
 Troposphere- The lowest layer of atmosphere in which all weatheric
changes take place.
 Stratosphere-The layer of the atmosphere in which temperature remains
constant
 Mesosphere-Middle layer of the atmosphere in which meteorites burn
in it after entering it.
 Thermosphere-Layer in which temperature increase very rapidly
ionosphere is a part of it. This helps in radio transmission.
 Exosphere-The upper most layer of the atmosphere mixing with space
above.
 Temperature –Degree of hotness and colness of the air is known as
temperature.
 Insolation-The portion of solar heat and energy which is received on the
surface of the earth is called insolation(incoming+solar+radiation)
 Air pressure: Air has weight and it exerts pressure This is called air
pressure.
[Time: 20 minutes
MI: Verbal
RBT: Application]
(b)Writing Task : Read Lesson 4, and Explain the following terms: (2 marks)
a.Permanent winds-Wind blowing in a fixed direction thorughout the year
b. Periodic winds- Winds which blow periodically from different directions
i.e. Monsoon winds, valley and mountain winds. Sea breezes
c.Local winds-Winds which blow during a particular period in a small area.
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d.Humidity- Moisture in the air is called Humidity.
e.Moisture- Water vapour present in the air is termed as moisture.
[Time: 20 minutes
MI: Verbal; Logical; Intrapersonal
RBT: Understanding]
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