(Geography) Chapter 8: India : Climate, Vegetation and Wildlife

Introduction 
    Weather is the day to day changes in our atmosphere in terns of temperature, moisture, wind, sun, cloud, rainfall and atmospheric pressure Weather conditions vary from place to place. Perhaps it is hot and rainy where you live but at the same time in other        parts of the world it could be cloudy and rainy or may be snowing. Weather changes in a short span of time. It may be bright and sunny in the morning, and cloudy in the afternoon. Thus, weather is the atmospheric condition in a particular area over a short          period of time.
    Climate refers to the weather conditions prevalent over a large area for a long period of time (say 25 years). 

Factors influencing climate
    Latitudes: The climate of a place depends upon its location on the earth. Places on the earth which are near to the equator are hot because here the sun's rays fall vertically. They are said to have a tropical climate. Places in the polar regions are cold                because the sun's rays fall at a slanting angle.
    Height above sea level : The temperature decreases with increase in altitude. For every 1, 000 metres of ascent there is a drop in temperature of 6°C. This is known as the Lapse Rate.
    Relief features :  Himalayas in the north and the seas surrounding the peninsula have played a major role in influencing the climate of India. The Himalayas prevent the cold winds from the Tibetan plateau to enter India. The mountain slope facing the rain-        bearing clouds receive rain and is called the windward side. The other side is the leeward side and receives less rainfall. This is the reason that Mumbai being on the windward side receives higher rainfall, and Pune being on the leeward side receives less          rainfall.
    Distance from the sea : Places near the sea receive cool breeze. This makes the climate pleasant and equable. It is neither too hot nor too cold in the coastal areas. The coastal areas are also humid. Humidity is the amount of water vapour contained in a        given volume of air.
    In places away from the sea, summers are very hot and winters are very cold. This kind of climate is called extreme climate and it is found in deserts.

Formation of Cyclones
    In October and November there is a gap between the rainy season and winter. It is during this season that cyclones form over. A cyclone is a huge storm that originates at sea in the tropical zone. It is characterized by a large low pressure centre and               strong winds spiraling inward and upward. The coastline of India is vulnerable to cyclones, particularly the east coast. Cyclones in this area may come in the months of April–May or October–December. These cyclones are very destructive as they bring           high speed winds and heavy rainfall in the densely populated deltaic regions of the Godavari, Krishna and Caveri.

Distribution of Rainfall
    Monsoon winds are irregular and not punctual. These winds can cause floods in one part and drought in another part simultaneously. Cherrapunji and Mawsynram in Meghalaya have more than 800 cm of annual rainfall, and places like Jaisalmer in               Rajasthan receive rainfall less than 12 cm, The western coastal plains and the north-east region receive more than 200 cm of rainfall while Gujarat, Rajasthan, Punjab and Haryana bordering it receive rainfall less than 60 cm. The Deccan Plateau also             receives less rainfall. Tamil Nadu receive less rainfall from the south-west monsoon winds. November and January is the rainy season here. On an average the country receives an annual rainfall of 120 cm.

CYCLE OF SEASONS IN INDIA
(1)    The Cold Weather Season – The cold weather season starts in India in early December and lasts upto February. January and February are the coldest months. Then temperature remains cool and dry. It is cool because the sun's rays do not fall directly.             The atmosphere is dry because the winds blow from the land and have no moisture. The temperature decreases from south to north. It varies from 10°C to 25°C. Temperature is between 10°C to 15°C in the northern India and about 25°C in the southern             India.
         During winter the north-east monsoon winds blow over India. A high pressure area develops in the northern plains due to cold climatic conditions from where the winds start blowing towards the areas of low pressure over the sea. While passing over the              sea (Bay of Bengal), they pick up moisture and cause heavy rainfall on the coast of Tamil Nadu during this season. The second region to receive rainfall in winter is the north-west part of India. It receives rainfall from the 'Western Disturbance

(2)    The Hot Weather Season – This season lasts from March to May. It is very hot during this season because the sun shines vertically over India. The highest day temperatures occur in the Deccan Plateau (38°C), Gujarat (43°C) and north-west of India (48°C) respectively. The rising temperature leads to the formation of low pressure area in the north-west of India. Because of this low pressure the moist winds from the Arabian Sea begin to blow towards land and cause pre-monsoon showers in Chhota Nagpur, Kerala and Western Ghats. But the north-west areas remain dry and hot winds, called 'loo', engulf the whole area. Sometimes dust storms in the Punjab, Haryana and U.P. are followed by light rain and cool breeze which lower the temperature to a great extent.

3.    South–West Monsoon Season or Advancing Monsoon Season – During the months of June to September the south-west monsoon winds blow northwards in two branches from the Arbian Sea and the Bay of Bengal. They give rainfall to the whole of northern India. The winds blow from the oceanic high pressure areas towards the low pressure areas of the land and give heavy rainfall. The Arabian Sea branch causes heavy rainfall, exceeding 300 cm along the coastal area of the Western Ghats, but this rainfall decrease as the monsoons go further. Thus the Deccan Plateau and the Eastern Ghats receive less rainfall as they are situated in the rain shadow area.

(4)    The Retreating Monsoon Season – This season runs from October to November. In this season the sky is usually clear and humidity is low. At this time the monsoons start retreating. The months of October and November form a period of Insnsition from hot rainy season to dry winter condition. The lower temperatures on the plains give rise to gradual increase in pressure and as such the monsoons retreat from most part of North India. Tamil Nadu receives high rainfall from these winds during this period (winter). The retreating monsoons are laden with moisture when they pass over the Bay of Bengal and cause rainfall in Tamil Nadu.

NATURAL VEGETATION
        India possesses a great variety of natural vegetation. We have about 47,000 plant species. According to an estimate India is tenth in the world and fourth in Asia in plant diversity. Flowering plants alone number 15,000 in India.
1.    Tropical Evergreen Rainforests – Evergreen forests are found in regions with rainfall above 300 cm. The climate is highly moist and humid. The temperature is even. The dry season is very short. These forests are of equatorial type. They are commonly            found in the Western Ghats and hills of Assam . Important trees of evergreen forests are oak, chestnut, deodar, cedar, chir and pine etc. The trees are often very high (about 100 metres). They have hard wood and broad leaves, and remain green all the              year round.

2.    The Tropical Deciduous Forests or the Monsoon Forests – These forests are the most widespread forests of India. They extend from the Western Ghats in the south to the Shivalik Hills in the north. They are found in areas where the rainfall is between        100 to 200 cm. The trees of these forests shed their leaves during the hot season before the monsoons. The main types of trees include teak, sal, sandalwood, rosewood, ebony, shisham, deodar, khair, Mahua, bamboo, etc. These trees provide                           valuable wood for making furniture and constructing buildings.

3.    The Thorn Forests – These forests are found in regions with less than 100 cm of rains per year. They often consist of stunted forests and bushes. The trees have long roots, small fleshy leaves and often sharp spines. They are stunted and widely spread.         Mainly two kinds of vegetations are found in these forests. Kikar and wild palm are found in areas with moderate rainfall. Scrubs, shrubs and thorny bushes are found in regions having scanty rainfall. This type of vegetation is found in Rajasthan, Punjab,             Haryana, Gujarat and the dry parts of the Deccan Plateau and Madhya Pradesh.

4.    The Tidal Forests or Mangrove forests – These forests are mainly found along the deltas of the rivers, especially the deltas of the Ganga, Mahanadi, Godavari and Krishna rivers. Their dense growth depends on the tidal waters which flood the land                   during the high tides. Mangrove and sundari trees are the common trees found in the Ganga delta in Bengal . It is also called the Sundarbans. Casurina is another important tree of these forests. The hard wood of these trees is very useful for building boats.

5.    Mountain Forests Vegetation of the Himalayan Region – The vegetation in the Himalayan region varies with height or altitude. It changes according to altitude upto the snow line. There are tropical deciduous forests at the foothills . Sal is the most                 common tree of this region. Above the tropical deciduous forests is found the sub-tropical hill vegetation. The green oak, chestnut and chir-pine are the common trees of this region. Coniferous forests are found at the heights between 1,600 and 3,300                 metres. Blue pines, cedars, silver firs and deodar are the common trees of this region.

WILDLIFE IN INDIA
    Leopards are found in the jungles of the terai, i.e. the Asam-Myanmar border, and in Madhya Pradesh. Hyenas, cheetah and jackals are wide spread in the forests of North India. Elephants are found in the forests of West Bengal, Assam, Madhya                    Pradesh,Kamataka, Kerala, Tamil Nadu and in the terai regions, i.e. at the foothills of the Himalayas. The one-horned rhinoceros is an endangered species. It is confined to the protected areas of the Kaziranga Forets and Manas National Parks of Assam.       The one-horned rhinocero can also be seen in the Jaldapara Wildlife Sanctuary in West Bengal.
   Various species of birds are also found in India: of which many are striking ones. Cranes, parrots, mynahs, owls, kites, pigeons, doves, bulbuls, crows and honey eaters are the main Indian birds.
   Vultures and kites arc found in large numbers in India. They arc very useful as scavengers. Many migratory birds such as pelicans, Siberian cranes, flamingoes, curlew and storks migrate to India in winters and return home in March. The Bharatpur Bird         Sanctuary in Rajasthan is one of those Indian bird sanctuaries where some of these migratory birds appear in winter.
   Reptiles such as crocodiles and snake like cobra, karait, python and many others are found in India. The Indian forest are also populated with house lizards and chameleons.

  Steps taken to Conserve Natural Vegetation and Wildlife.
  Many steps have been take to conserve national vegetation and wildlife. Biosphere reserves have been set up in various parts of India where wild animals and birds are kept in their natural habitat. Nilgiri at the junction of Karnataka, Tamil Nadu and Kerala,    and Nanda Devi in Uttar Pradesh are some such biosphere reserves. India has 86 national parks, 480 wildlife sanctuaries and 35 zoological gardens to protect wildlife. Periodic censuses are being taken to find out the latest position of some rare species so    that they can be preserved for our future generations. The killing of wildlife has been banned by the government. Special Forest Officers have been appointed to catch illegal animal hunters.

Key Words
•    WEATHER : day to day changes in the temperature, pressure, rainfall etc. in the atmosphere.
•    CLIMATE : the average weather patterns in places over many years.
•    ALTITUDE : height above sea level.
•    LAPSE RATE : drop in temperature with increasing altitude — 6°C for 1,000 metres.
•    MONSOON : seasonal winds that originate in tropical sea and bring in rain.
•    Loo : the hot and dry, local winds in summer over the northern plains.
•    OCTOBER HEAT : the period of high humidity after the monsoon rains.
•    RAIN FORESTS : dense forests with close canopy in areas of heavy rainfall.
•    DECIDUOUS TREES : hardwood, broad leaved trees.
•    CONIFEROUS TREES : softwood one shaped trees.
•    ALPINE VEGETATION : vegetation on high altitude (of mountains).
•    TIDAL FORESTS : forests grown in deltas where the fresh water of river mixes up with saline water of sea at the times of high tides.