Climate of India PDF

# CLIMATE OF INDIA * India has a climatic contrast because it has places like Leh where temperature drops down to -45 degrees in winter and goes as high as 55 degrees in western deserts during summer. Also, variation is seen in the amount of precipitation for example: In Mawasyram rainfall is highe...

# CLIMATE OF INDIA * India has a climatic contrast because it has places like Leh where temperature drops down to -45 degrees in winter and goes as high as 55 degrees in western deserts during summer. Also, variation is seen in the amount of precipitation for example: In Mawasyram rainfall is highest and in the western desert it is very less. ## Factors affecting the climate of India: 1. **Latitude:** India is located between 8 degrees 4 minutes north to 37 degrees 6 minutes north latitude. The Tropic of Cancer passes through the middle of India dividing it into tropical and temperate zones, hence temperature goes very high during summer except in the high altitudes and the coastal regions. 2. **Himalayas:** are responsible for: * Protecting the Indian sub-continent from the cold Siberian winds coming from the north of Asia. * Obstructing the south-west monsoon winds thereby causing heavy rainfall in the northern plain of India. 3. **Distance from the Sea:** Coastal regions have an equable/moderate type of climate due to the influence of the sea, also have very less range of temperature whereas, places far from the sea in the plain have extreme types of climate/very hot or very cold climate according to the season. Major places along the coast are Chennai, Mangalore, Cochin, Vishakapatnam, Mumbai, Kanyakumari, Kolkata, Paradeep, Pondicherry, Surat, and Panaji, Goa. 4. **Altitude:** Higher the altitudes lower the temperature. Place like Ooty situated near the equator has a low temperature compared to the surrounding places situated close to it in the plain. Similarly, Himalayas has a large number of hill stations where the temperature is low throughout the year. Some of the hill stations are Nainital, Shimla, Darjeeling, Gangtok, Almora, and Srinagar. 5. **Relief:** Western Ghats lying parallel along the western coastal plain forces the moist south-west monsoon winds from the Arabian Sea to shed most of its moisture along the western slope and the western coastal plain. The windward side of the mountain range also causing less rainfall along the leeward side or rain shadow region. Example: Mumbai receives 190 cm rainfall whereas Pune about 160 km receives only 50 cm rainfall. ## Four seasons of India: * Cold weather season from December to February * Hot Dry season from March to May * Season of s-w monsoon/advancing monsoon from June to September * Season of retreating monsoon/N-E monsoon from October to November. ## Cold weather season from December to February: 1. **Characteristics:** Clear sky, Low temperature and low Humidity, High range of temperature, slow cool winds in the north, cold, dry winds. 2. **Temperature conditions in the North:** Temperature drops below 21 degrees in the northern part. January is the coldest month. Temperature in the gangatic plain varies from 2.5 degrees Celsius to 17.5 degrees Celsius. Dras valley in the Kargil is the coldest with a minimum of -45 degrees Celsius. 3. **Temperature conditions in the South:** The areas below the tropic of cancer remain warm. The isotherm of 20 degrees Celsius runs almost parallel to the tropic. Further south, the temperature is above 25 degrees Celsius. 4. **Pressure conditions and wind directions**: Due to the apparent migration of the sun towards south, rays of the sun falling over India is oblique, as a result High pressure is formed over the land due to the low temperature and low pressure is formed over the surrounding water bodies due to high temperature. As such offshore winds starts blowing towards low pressure areas in the sea. These cold dry winds blow towards Bay of Bengal due to the peninsular plateau and which are carried away by the N-E trade winds towards the S-E of India. 5. **Rainfall during winter season:** * **Coromandal Coast in Tamil nadu:** Offshore, Northeast monsoon winds blow from high pressure region to low pressure centered at Bay of Bengal carry moisture and are carried away by N-E trade winds towards S-E of India i.e. Coromandal Coast Tamil nadu. S-E tip of Andhra Pradesh get heavy rainfall accompanied by strong winds. Rainfall also occurs in eastern part of Kerala and Karnataka. Average rainfall is 70-75 cm. This occurs from October till December. * **Rainfall in the North-West:** Westerly shallow cyclonic depressions originating in the Mediterranean Sea are known as western disturbances. These winds reach India crossing West Asia, Iran, Afghanistan, and Pakistan before they reach N-W of India. Rainfall occurs from December to February. Snow fall in higher region of Jammu and Kashmir and Himachal Pradesh occurs. Rainfall occurs in Punjab, Haryana, Uttar Pradesh. ## Hot dry season from March to May: 1. **Characteristics:** Dry weather and excessive heat, Sun shines overhead the tropic of cancer, range of temperature is very high in the N-W region. Thunderstorms accompanied by the dusty winds are common. 2. **Temperature conditions over the land:** During this season the temperature is very hot over the land hence low pressure is created whereas high pressure over the surrounding sea. The temperature goes to 45 to 50 degrees Celsius in the north and north-west of India and about 38 degrees to 40 degrees Celsius in the south. 3. **Pressure conditions and wind directions:** Due to the high temperature over the land low pressure trough develops between the Thar and the Chotanagpur. High pressure develops in the surrounding seas due to the high pressure development, these moisture carrying winds are attracted towards the Indian peninsular region changing its direction from S-E to N-E. ## Local winds: * **Kali Baisakhi:** Means the calamity in the month of Baishakhi (in Bengali). They are also called 'norwesters' because they blow in north-west direction. These local winds are accompanied by thunderstorms and bring heavy rainfall. Rainfall occurs in the month of April/May. It helps in tea cultivation in Assam, jute and rice in west Bengal. * **Loo:** Loo is hot dusty dry winds, some of them called 'sand storms' which blow particularly in the month of May and June in the Northern plain. Temperature rises up to 45 degrees to 50 degrees, which may cause sunstroke. It brings severe drought conditions. It does not affect the coastal and the areas of high altitude. It affects the states of northern plain like Bihar, Punjab, Haryana and Uttar Pradesh. * **Mango Showers:** These occur in south India during April/May. These are pre-monsoon showers in the south which helps in the growth of mango, tea and coffee plants. In Karnataka it is called 'Cherry blossom' because it helps coffee plant to grow berries. ## The Rainy Season or The Season of The South-West Monsoon: 1. **Characteristics:** Distribution of the rainfall is not uniform. Tamil nadu does not receive rainfall. Duration of the monsoon varies from 2 to 4 months. * Sometimes it causes floods due to heavy rainfall, especially in Assam, Bihar, U.P., while the other parts may be reeling under severe drought due to scanty or no rainfall, especially in Rajasthan. * It is controlled by orography. The effects caused due to the Himalayas and Western Ghats on the amount and distribution of rainfall, and the inability of the Aravalis to cause rainfall in Rajasthan. * Sometimes tropical depression (low pressure system) originates in Bay of Bengal due to the local variations of heat and moisture during the month of October and November. 2. **Origination of S-W Monsoon:** The sun shines overhead the Tropic of Cancer from March to May; the differential heating of the land and sea brings about a seasonal low pressure trough centered between Thar and Chotanagpur region. As a result, high pressure gradient builds up between the hot north India with intense low pressure. The low pressure area attracts the south east trade winds blowing in the southern hemisphere. As such after crossing the equator these winds are deflected towards Indian sub-continent as south-west monsoon winds. These winds blow from south-west to north-east carrying large amount of moisture from the Arabian Sea. 3. **Advance of The Monsoon:** It breaks first in the coast of Kerala in the Malabar in the first week of June. By the first and second week, they overrun whole of Kerala on the west, Karnataka and Andhra Pradesh proceeding towards north-east. * Also, by the beginning of the second week they reach Mumbai then Ahmedabad, Bhopal, and by July first they cover most of Kachch, Eastern Rajasthan, Whole of U.P, Haryana, Himachal and Eastern Punjab. ## The S-W Monsoon Divides into two branches due to tapering topography of peninsular India: 1. **The Arabian Sea Branch:** * This branch of the S-W Monsoon strikes first at the Malabar Coast of Kerala, causing heavy rainfall along the windward side of the Western Ghats. * Leeward side of the Western Ghats receives very little rainfall for example: Mahabaleshwar situated on the windward side of the Western Ghats receives 250 cm of rainfall, whereas Pune, only a few km away, receives less than 70 cm. * Amount of rainfall goes on decreasing as Arabian sea branch moves northward. * Arabian sea branch causes very little rainfall in Rajasthan because: * The Aravali's alignment is parallel to rain bearing Southwest Monsoon winds and as such they do not offer any obstruction. * Saturation of the moisture laden winds does not occur as the heat in the desert region increases their capacity to hold moisture. 2. **The Bay of Bengal Branch:** * Andaman and Nicobar islands are the first to receive rainfall due to the Bay of Bengal Branch. * Bay of Bengal branch moves towards North-eastern states. * Rain is intercepted by the north-east Himalayas including Garo, Khasi, and Jaintia. * Mawasynram, 16 km west of Cherrapunji, gets the heaviest annual rainfall in the world (1187.3 cm). This is relief rainfall. Shillong on the other hand lying in the rain shadow of Khasi hills gets little rainfall. * The remaining portion of the bay of Bengal branch is deflected towards west along the Himalayas. However, rainfall keeps on decreasing as it proceeds towards the Ganga valley. ## The Retreating South-West Monsoon (October-November): 1. **Characteristics:** Low pressure created during summer is weakened with decreasing temperatures, giving way to high pressure on land and low pressure on surrounding seas. It is a transition period between the hot rainy season and cold dry season in the month of October and November. * Tropical cyclones occur over the bay of Bengal and rarely over the Arabian sea, which causes tremendous loss of life and property. * Rainfall in Tamilnadu and Andhra Pradesh is caused by retreating monsoon coming from the bay of Bengal, accompanied by north-east trade winds. * High humidity and high temperature during the month of October. Thus this sultry and oppressive weather is often referred to as “October Heat". 2. **Origin:** In September, with the apparent movement of the Sun towards south, the low pressure in central India starts weakening, and is no longer able to attract the monsoon winds towards land. Slowly, as the high pressure begins to build over mainland, and subsequently with low pressure over the sea, the south-west monsoon begins to withdraw from the mainland India. South west monsoon had travelled towards the north, now it retreats towards south. This process starts in October, and is over by the end of November. ## Amount of rainfall depends upon: * Direction of moisture laden winds. * Relief features. * Cyclonic depressions due to the difference in pressure. ## Rainfall over 200 cm in the north of tropic of cancer: * Garo-Khasi, Jaintia and Lushai hills. States: Meghalaya, Assam, West Bengal, Bangladesh and Arunachal Pradesh. * South of Tropic of Cancer: Konkan coast, Malabar coast States: Kerala, Goa, Karnataka and Maharashtra. ## Areas with 100-200 cm rainfall: * In the north: Ganga valley. States: Bihar, West Bengal, Madhya Pradesh. * In the south: North of Andhra Pradesh, and southern parts of Tamil Nadu. ## Areas with 50-100 cm rainfall: * In the North: Upper Ganga valley and Eastern Rajasthan. States: Punjab, Haryana, and Kashmir. * In the south: Southern Deccan comprising the plateau region of Karnataka. States: Andhra Pradesh and Tamil Nadu. ## Areas with less than 50 cm rainfall: * In the North: Western Rajasthan, northern most part of Kashmir, and southern Punjab. * In the south: Central Deccan region, leeward side of Western Ghats. ## Comparison with regard to temperate range: * Low temperature range: Extreme continental climate. * High Range: Moderate/Equable climate. ## Annual Rainfall: * Sum of all values in 12 months. ## Average Rainfall = Annual Rainfall / 12 | Station | Month | J | F | M | A | M | J | J | A | S | O | N | D | |---|---|---|---|---|---|---|---|---|---|---|---|---|---| | A | Temp (°C) | 14.4 | 16.7 | 28.3 | 30.0 | 33.3| 33.3 | 30.0 | 24.4 | 28.9 | 25.6 | 19.4 | 15.6 | | | Rainfall (cm) | 2.5 | 1.5 | 1.3 | 8 | 7.4 | 19.3 | 17.8 | 11.9 | 1.3 | 0.2 | 1.0 | 1.0 | | B | Temp (°C) | 24.4 | 24.4 | 26.3 | 28.3 | 30.0 | 28.9 | 27.2 | 27.2 | 27.2 | 27.8 | 27.2 | 25.0 | | | Rainfall (cm) | 0.2 | 0.2 | 1.8 | 50.6 | 61.0 | 36.1 | 24.8 | 4.8 | 1.0 | 1.0 | * **Calculate the temperature range of station A + station B.** * **Calculate the annual rainfall of station A + station B.** * **Calculate the average rainfall of station A + stations B.** * **On the basis of temperature range of station A & B explain the type of climate.** 1. **Temp. Range (A)** = 33.3 - 14.4 = 18.9 °C. **Temp. Range (B)** = 30 - 24.4 = 5.6 °C 2. **Annual Rainfall (A)** = 65 cm. **Annual Rainfall (B)** = 181.3 cm. 3. **Avg Rainfall (A)** = 65 / 12 = 5.4 cm (avg) **Avg Rainfall (B)** = 181.3 / 12 = 15.1 cm 4. *A Continental climate* *B Equable climate*