Q2 of 8 Page 81

Answer the following questions in about 30 words.

(i) How does the unequal distribution of heat over the planet earth in space and time cause variations in weather and climate?


(ii) What are the factors that control temperature distribution on the surface of the earth?


(iii) In India, why is the day temperature maximum in May and why not after the summer solstice?


(iv) Why is the annual range of temperature high in the Siberian plains?


(i) The air and the ocean currents are responsible in the variations in weather and climate. As the earth receives uneven isolation from the sun due to its tilt axis, the areas get unevenly heated. More over the air and water currents carry the heat from one area to other and therefore the climate changes.

(ii) The factors that control temperature distribution on the surface of the Earth are as follows:-


• The latitude of the place- The temperature depends on the isolation received which differs from place to place


• The altitude of the place- The temperature decreases with increase in altitude known as normal lapse rate i.e. 1°C per 167 m.


• Distance of the sea- This depend on the land and sea breeze which regulates the temperature of a place.


• Air-mass and Ocean currents- The air and ocean currents regulates the temperature of a place.


(iii) India is located around the northern hemisphere. Summer sets in India from March end. So in May the summer is at its peak therefore the day temperature is maximum. On 21st June, the sun rays fall directly on the northern hemisphere i.e. 23.5°N. After 21st June, the monsoon sets in India which brings a cooling effect to the country.


(iv) Annual range of temperature is the difference between the mean temperature of the warmest and the coldest months. In Siberia the mean January temperature both at 80°N and 50°N is -20°C and in July it is more than 10°C. Therefore the annual range of temperature is high.


More from this chapter

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1

Multiple choice question.

Make correct pairs from the following two columns.



1

Multiple choice question.

The main reason that the earth experiences highest temperatures in the subtropics in the northern hemisphere rather than at the equator is:


3

Answer the following questions in about 150 words.

(i) How do the latitude and the tilt in the axis of rotation of the earth affect the amount of radiation received at the earth’s surface?


(ii) Discuss the processes through which the earth-atmosphere system maintains heat balance.


(iii) Compare the global distribution of temperature in January over the northern and the southern hemisphere of the earth.


1

Select a meteorological observatory located in your city or near your town. Tabulate the temperature data as given in the climatological table of observatories:

(i) Note the altitude, latitude of the observatory and the period for which the mean is calculated.


(ii) Define the terms related to temperature as given in the table.


(iii) Calculate the daily mean monthly temperature.


(iv) Draw a graph to show the daily mean maximum, the daily mean minimum and the meantemperature.


(v) Calculate the annual range of temperature.


(vi) Find out in which months the daily range of temperature is the highest and the lowest.


(vii) List out the factors that determine the temperature of the place and explain the possible causes for temperature variation in the months of January, May, July and October.


Example


Observatory: New Delhi (Safdarjung)


Latitude: 28°35°’ N


Based on observations: 1951 - 1980


Altitude above mean sea level: 216 m



Daily mean monthly temperature


January


May


Annual range of temperature


Mean Max. Temperature in May - Mean Temperature in January


Annual range of temperature = 32.75°C – 14.2°C = 18.55°C