Weather: The day to day changes in atmosphere is called weather. Weather includes changes in temperature, sunshine and rainfall. A day can be comfortably cold in the morning and may change to unbearably hot afternoon.
There are four major seasons in India, viz. cold season, hot season, southwest monsoon and retreating monsoon.
The winter season continues from December to February in India. During this season, the sun rays do not fall directly on India. As a result, the temperature remains low in northern India during this period.
The summer season continues from March to May in India. During this season, the sun rays fall more or less directly on India. Due to this, the temperature remains high during this period. Hot and dry winds (called loo) blow during the day in northern India.
The rainy season falls from June to September. The onset and advancement of monsoon takes place in this season. The monsoon winds blow from the Arabian Sea and Bay of Bengal towards the Indian Peninsula. These winds carry moisture with them. When the moisture laden wind strikes the mountain barriers, it results in rainfall in India.
The word monsoon has come from the Arabic word ‘mausim’ which means season.
This season falls in October and November. During this season, the monsoon winds move from the mainland to Bay of Bengal and hence it is called the retreating monsoon. During this season, the southern parts of India receive rainfall. Rainfall happens especially in Tamil Nadu and Andhra Pradesh during this season.
The monsoon has high importance for India. Agriculture in India is dependent on monsoon. A good monsoon means good harvest. A bad monsoon results in poor harvest. Farmers become very happy when there is good monsoon.
Overall pattern of weather at a place is called climate. For this, weather pattern of at least 20 years is taken into consideration. The climate of India is called monsoon climate. This is hot and humid in most parts of the country.
Factors which affect the climate of a place are; location, altitude, distance from the sea and relief. Since India is a large country, there is wide variation in climate from one place to another. For example; Rajasthan is generally hot and dry, while Kashmir is very cold. There is wide variation in temperature in the northern plains. On the other hand, the climate of Mumbai and Kolkata is moderate throughout the year. Mawsynram in Meghalaya receives highest rainfall in the world, while Jaisalmer in Rajasthan receives negligible rainfall.
Plants which grow on their own without human intervention are called natural vegetation. Natural vegetation depends on various climatic conditions and especially on rainfall. There are five types of natural vegetation in India.
Tropical evergreen forest, Tropical deciduous forest, Thorny bushes, Mountain vegetation and Mangrove forests
Tropical rainforest is found in those areas which receive heavy rainfall. The tropical rainforest is so dense that sunlight does not reach the ground. The trees of the tropical rainforest shed their leaves at different times of the year. Due to this, the forest always appears green. Hence, such a forest is called evergreen forest.
Important Trees: Mahogany, ebony and rosewood.
Tropical Rainforest in India: Andaman and Nicobar Islands, parts of North-Eastern states and a narrow strip of the western slope of the Western Ghats.
These are also called monsoon forests. The trees of deciduous forest shed their leaves at a particular time of the year. Hence, such a forest is called deciduous forest.
Important Trees: Sal, teak, peepal, neem and shisham.
Tropical Deciduous Forest in India: Madhya Pradesh, Uttar Pradesh, Bihar, Jharkhand, Chhattisgarh, Orissa and parts of Maharashtra.
This type of vegetation is found in dry areas. The leaves are in the form of spines. This helps the plant to reduce loss of water.
Important Trees: Cactus, khair, babool and keekar
Thorny Bushes in India: Rajasthan, Punjab, Haryana, Eastern slopes of Western Ghats and Gujarat
Different types of species are found in the mountains at different altitudes. At the height between 1500 meter and 2500 meter, most of the trees are conical in shape. Due to this, they are called coniferous trees.
Important Trees: Chir, pine and deodar.
Mangrove plants can survive in saline water. They are mainly found in the Sunderbans in West Bengal and in the Andaman and Nicobar Islands. Sundari is a well known tree in the mangrove forest of Sunderban.
Loss of Natural Vegetation: Humans have destroyed a large tract of forest. We are recklessly cutting trees for various purposes. Forests are cleared for making way for agriculture and for making townships and factories. This is creating environmental problems for us. Van Mahotsav is being organized to educate people about the importance of forests.
Due to large scale cutting of forests, natural habitat of many wild animals has become less. Many animals are in danger of becoming extinct. Many animals have already become extinct.
Extinct Species: A species which no longer exists is called and extinct species.
Endangered Species: A species which is in danger of becoming extinct is called endangered species.
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