8th Social Science Guide Geography Unit 2 Weather and Climate

8th Social Science – Geography Guide Lesson 2 Weather and Climate

8th Standard Social Science Guide Geography Unit 2 Weather and Climate English Medium Guide Book Back Question and answers download pdf. 8th STD All Subject Guide. Tamil Nadu Start Board Syllabus Samacheer kalvi 8th std all Lesson / Units question and answers. 8th Social Science TEXT Books download pdf. Tamil and English Text books. 8th Standard Tamil Guide.

 

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8th Social Science Guide Geography Unit 2 Weather and Climate

I. Choose the correct answer

1. Earth’s atmosphere contains about ________ percentage of nitrogen and oxygen.

1. 78% and 21%
2. 22% and 1%
3. 21% and 0.97%
4. 10% and 20%

Ans : 78% and 21%

2. ———– is generally defined as the average conditions of the weather of a place or a region.

1. earth
2. atmosphere
3. climate
4. sun

Ans : climate

3. The earth receives energy from ———-.

1. current
2. electro magnetic radiation
3. waves
4. heat

Ans : electro magnetic radiation

4. Which one the following represents places with equal amount of rainfall

1. isotherm
2. isohel
3. isobar
4. isohyets

Ans : isohyets

5. __________ is used to measure the humidity.

1. anemometer
2. barometer
3. hygrometer
4. thermometer

Ans : hygrometer

II. Fill in the Blanks.

1. ______________ refers to the condition of atmosphere for a short period of time.Ans : Weather
2. The scientific study of weather is called ______________.Ans : Meterology
3. The highest temperature ever recorded on the earth is ______________.Ans : 56.7°C
4. ______________ is a ratio between the actual amount of water vapour and the maximum amount of water vapour the air can hold.Ans : Relative humidity
5. _____________ and_____________ are measured by anemometer and wind vane respectively. Ans : Wind speed and Wind direction

6. __________ are imaginary lines which connect the same temperatures of different places.Ans : Isotherms

III. Match the following

1. Climate – Locating and Tracking Storms
2. Isonif – Cyclone
3. Hygrometer – Equal Snowfall
4. Radar – Long Term Changes
5. Low Pressure – Humidity

Ans : 1 – D, 2 – C, 3 – E, 4 – A, 5 – B

IV. State true or false :

1. The atmosphere is a layer of gases surrounding the planetAns : True.
2. The Scientific study of weather is called ClimatologyAns : False.
3. Isohel refers equal sunshineAns : True.
4. Humidity is calculated by Aneroid BarometerAns : False.

V. Answer in brief

1. Define‘weather’

• Weather is the day today conditions(state) of the atmosphere at any place as regards sunshine, temperature, cloud cover. Wind fog condition, air pressure, humidity, precipitation and such other elements.

2. What is insolation?

• Insolation is the solar radiation that reaches the earth’s surface. The earth and its atmosphere get heated from the sun through insolation.

3. What is meant by atmospheric pressure?

• The weight of air above a given area on the earth’s surface is called atmospheric pressure or air pressure.

4. Write a short note on “Planetary winds”

• Planetary Winds are the ones which blow almost in the same direction throughout the year. So, they are called as Permanent or planetary winds.
• Trade winds, Westerlies and polar easterlies are the types of prevailing winds.

5. What are “Isolines”?

• Distribution of weather elements are shown by means of Isolines on maps. Isolines are lines which join the places of equal values of weather elements.

VIII.Distinguish the following:

1. Weather and climate.

Weather	Climate
1. Weather is the day to day condition of the atmosphere at any place	Average condition of the weather of a place or a region.
2. Refers to short periods like a day, a week, a month etc.,	Determined by measuring weather elements for a long period of time usually for 35 years
3. Sunshine, temperature, cloud cover, wind, fog condition, air pressure, humidity precipitation are some weather elements	Latitude, Altitude, direction of winds, distance from the sun, Ocean currents are some of the factors determining climate.

2. Absolute and relative humidity.

Absolute humidity	Relative humidity
1. Mass or weight of water vapour present per unit volume of air.	Ratio between the actual amount of water vapour present in the air and the maximum amount of water vapour it can hold at a given temperature.
2. Expressed usually in grams per cubic metre of air.	Expressed as a percentage.

3. Permanent and seasonal winds.

Permanent winds	Seasonal winds
1. The ones which blow almost in the same direction throughout the year.	Winds which change their direction according to season in a year. Blow from sea to land in summer and land to sea in winter
2. Also called Planetary winds. Example Trade wings, Weather winds	Also called Monsoon winds. Example North east monsoon winds, South west monsoon winds

VII. Give reasons.

1. The Weather and climate in different regions vary.

• Angle of the sun’s rays, the length of daytime, altitude, distribution of land and water bodies, location and direction of mountain ranges, air pressure, winds and ocean currents are the major factors which affect the weather and climate of a region.

2. Temperature decreases with increase in altitude.

• Temperature varies both horizontally and vertically. Temperature always decreases with increasing height is known as Lapse rate which is 6.5 degree Celsius per 1000 meters in troposphere.

3. Mountain climbers carry oxygen cylinders while ascending peaks.

• With decreasing air pressure,the availability of oxygen to breath also decreases. At very high altitudes, atmospheric pressure and available oxygen get so low that people can become sick and even die. Mountain climbers use bottled oxygen when they ascend very high peaks.

VIII. Answer in a paragraph.

1. How is temperature measured?

Measuring Temperature:

• The temperature of a unit volume of air at a given time is measured in scales like Celsius, Fahrenheit, and Kelvin. Meteorologist measures the temperature by the Thermometer, Stevenson screen and minimum and maximum Thermometer.
• The energy received by the earth through insolation is lost by outgoing radiation.
• Atmosphere is mainly heated by outgoing radiation from 2 to 4pm. So the maximum temperature is recorded between 2 and 4 pm regularly and minimum temperature is recorded around 4 am before sunrise.

Mean Temperature:

• The average of maximum and minimum temperatures within 24 hours is called mean daily temperature [(87°F + 73°F)/2=80°F].
• Diurnal range of temperature is the difference between the maximum and minimum temperatures of a day. Annual range of temperature is the difference between the highest and lowest mean monthly temperatures of a year.

2. Write about the wind and its types.

The horizontal movement of air is called wind.

The wind systems are broadly categorized into three as follows.

1. Planetary winds
2. Seasonal winds
3. Local winds

Planetary Winds

• Planetary Winds are the ones which blow almost in the same direction throughout the year. So, they are called as Permanent or planetary winds. Trade winds, Westerlies and polar easterlies are the types of prevailing winds.

Seasonal winds

• Seasonal winds are those which change their direction according to season in a year. They are called as monsoon winds. These winds blow from sea to land during summer and land to sea during winter.

Local winds

• Local winds are the winds blow over a small area only during a particular time of a day or a short period of a year. Land and sea breezes are example of these winds.

3. List out the weather elements and associated measuring instruments.

Temperature, rainfall, pressure, humidity and wind are the major elements of weather and climate.

1. Temperature:

Measured in scales like Celsius, Fahrenheit and Kelvin. Meterorologists Measure the temperature by the Thermometer. Stevenson screen and minimum and maximum thermometer.

2. Rain:

Is a major component of the water cycle and is the source of most of the fresh water on the earth. Rainfall is measured by raingauge.

3. Air Pressure:

Meteorologist uses barometer/aneroid barometer to measure the air pressure. Barograms are used for recording continuous variation in atmospheric pressure.

4. Humidity:

Hygrometer is used to measure the humidity, (which comprises wet and dry bulbplate side by side in the Stevenson screen)