NCERT Geography Notes cl9 ch4 climate as ppt

PART 1 OF 2 NOTES ARE SHARED OF GEOGRAPHY NCERT CLASS IX CH4 CLIMATE

1. Differntiate between weather and climate. weather Atmospheric condition changes for a short period of time(from a few hours -2 days) and in a small area it is called weather. Weather is sudden and is unexpected Weather changes are expressed as clear sky, sunny day, cloudy, windy, pleasant day etc. climate Atmospheric conditions for a very long period (35-50 yrs.) over a very large area is called Climate. Climate is expected people wait for seasons to change. India has a Monsoon type of Climate where different seasons follow each other in a rrythmic cycle.

2. 2-Discuss the regional variations in the climatic condition of india with the help of suitable examples. Ans 2. India has Monsoon type of climate but there are perceptible variations in climatic conditions from region to region . For eg . Mercury touches 50*c during summers in the deserts of Rajasthan whereas at the same time it is 20*c in Pahalgam in J&K. The temperature may go as low as -45*c in Drass in Ladakh on a winter night whereas it is 22*c in Tiruvananthpuram at the same time. In Himalayas precipitation is in the form of snowfall whereas the rest of the country receives rainfall. The durinal range of temperature is high in Rajasthan as compared to coastal regions of India. Most of India receives rainfall from June –September whereas T.N coastal area receives rainfall in the months of October –November. Annual precipitation varies from 400cms. In MEGHALAYA to less than 10cms in western Rajasthan.

3. Explain different factors affecting the climate of a place. LATITUDE: AS TEMPERATURE DECREASES FROM THE EQUATOR TOWARDS THE POLAR AREAS HENCE THE PLACES WHICH ARE LOCATED IN THE EQUATORIAL REGIONS TEND TO BE HOTTER AS COMPARED TO PLACES AWAY FROM IT. IT IS BECAUSE THE AMOUNT OF SOLAR ENERGY RECEIVED VARIES DUE TO THE CURVATURE OF THE EARTH.

4. 2-ALTITUDE = HEIGHT OF A PLACE ABOVE THE SEA LEVEL AS THE TEMPERATURE DECREASESS 1* CELSIUS FOR EVERY 165 METERS OF ASCENT HENCE PLAINS ARE WARMER THAN HILLY AREAS THIS IS BECAUSE AS WE GO TO HIGHER ALTITUDES THE ATMOSPHERE BECOMES LESS DENSE AND SO IT CANNOT HOLD THE HEAT HENCE IT BECOMES COLDER WITH INCREASE IN ALTITUDE.

5. 3-PRESSURE AND WIND CONDITIONS AS WINDS BLOW FROM HIGH PRESSURE (COLD REGIONS) TO LOW PRESSURE (HOT REGIONS) AREAS THEY INFLUENCE THE TEMPERATURE AND RAINFALL OF AN AREA. PRESSURE AND WIND CONDITIONS OF AN AREA DEPEND UPON THE LATITUDINAL AND ALTITUDINAL LOCATION OF A PLACE OR ON THE TEMPERATURE OF A PLACE.

6. 4- DISTANCE FROM THE SEA- Due to the moderating influence of the sea the coastal areas have moderate climate whereas the landlocked areas have extreme climate.

7. 5-OCEAN CURRENTS THE WARM AND COLD OCEAN CURRENTS TEND TO WARM OR COOL THE TEMPERATURE OF COASTAL AREAS IF THE WINDS ARE ONSHORE

8. 6-RELIEF FEATURES IF A RELIEF FEATURE LIKE A HIGH MOUNTAIN LIE IN THE PATH OF RAIN BEARING WINDS THE WINDWARD SIDE OF THE MOUNTAIN RECEIVES RAINFALL WHEREAS DRY WINDS BLOW TOWARDS THE LEEWARD SIDE OF THAT MOUNTAIN AND THEREFORE IT IS ALSO CALLED A RAINSHADOW AREA. THEY ACT AS A BARRIER FOR COLD AND HOT WINDS HENCE HIGH MOUNTAINS ACT AS A CLIMATIC DIVIDE AND AFFECT THE CLIME OF A PLACE.

9. FACTORS AFFECTING CLIMATE OF INDIA 1- LATITUDE TROPIC OF CANCER THAT PASSES THROUGH THE CENTER OF INDIA DIVIDES IT INTO TWO CLIMATIC ZONES. THE LATITUDINAL LOCATION OF INDIA IS SUCH THAT THE NORTHERN HALF OF THE COUNTRY WHICH IS ABOVE THE TROPIC OF CANCER EXPERIENCES SUB-TROPICAL CLIMATE WHEREAS THE SOUTHERN HALF OF INDIA WHICH IS TO THE SOUTH OF TROPIC OF CANCER EXPERIENCES TROPICAL CLIMATE .

10. 2-ALTITUDINAL VARIATION India has mountains to the north, which have an average height of about 6000 METRES. India also has a vast coastal area where the Maximum elevation is about 30 metres . The Himalayas prevent the cold winds from Central ASIA from entering the subcontinent. It is because of these mountains that INDIA experiences comparatively milder winters as compared to central Asia .

11. 3-Pressure and surface winds INDIA LIES IN A REGION WHERE WINDS BLOW FROM N.ELY DIRECTION. FROM LAND TO SEA. SO THEY ARE DRY WINDS. BUT DURING SUMMERS THE LAND BECOMES A HIGHLY LOW PRESSURE AREA. SO A COMPLETE REVERSAL OF WIND DIRECTION TAKES PLACE AND FROM JUNE THE MOISTURE LADEN WIND CROSSES THE EQUATOR AND STARTS BLOWING TOWARDS INDIA CAUSING WIDESPREAD RAINFALL IN THE INDIAN SUBCONTINENT. THESE ARE CALLED SOUTH-WEST MONSOON WINDS.

12. 4- UPPER AIR CIRCULATION= JET STREAMS THEY ARE LOCATED OVER 27-30 * NORTH OF EQUATOR. THEY BLOW TO THE SOUTH OF THE HIMALAYAS THROUGHOUT THE YEAR EXCEPT SUMMERS. THEY CAUSE WESTERN CYCLONIC DISTURBANCES IN THE NORTH AND N.W PART OF INDIA THEY BLOW OVER PENINSULAR INDIA OVER 14* N LATITUDE. THEY COME TO INDIA DURING SUMMER MONTHS. (AMPHAN) THEY CAUSE CYCLONES AND HEAVY RAINFALL TO THE COASTAL AREAS OF INDIA SUB-TROPICAL WESTERLY JET STREAMS SUB-TROPICAL EASTERLY JET STREAM THESE ARE VERY HIGH SPEED WINDS 110-184 KM PER HR. THEY BLOW IN A NARROW BELT AT VERY HIGH ALTITUDE(12000 Mts.)

13. SUBTOPICAL WESTERLY AND EASTERLY JET STREAMS

14. 5-CYCLONIC DISTURBANCES WESTERN CYCLONIC DISTURBANCE EASTERN CYCLONIC DISTURBANCE THEY ARE HIGH ALTITUDE WINDS THAT ORIGINATE OVER THE MEDITERRANNIAN SEA. THEY ARE MOIST WINDS AND THEY BLOW TOWARDS NORTH AND NORTHWESTERN INDIA. THESE CYCLONES BRING RAINS DURING WINTER MONTHS IN THE NORTH AND NORTH WESTERN PARTS OF INDIA TROPICAL DEPRESSIONS ORIGINATE OVER THE ANDAMAN SEA ATTRACTS THE WINDS FROM THE EAST. THESE ARE VERY STRONG WINDS THAT BLOW TOWARDS THE EASTERN COAST OF INDIA. THESE WINDS CAUSES VERY HEAVY RAINFALL , THEY ARE DESTRUCTIVE AND HITS THE EASTERN COASTAL REGIONS IN THE MONTHS OF OCTOBER- NOVEMBER.