VI GEO GIST – INDIA : CLIMATE, VEGETATION AND CLIMATE

  • Weather is about day to day changes in the atmosphere. It includes changes in temperature, rainfall and sunshine.

Broadly, the major seasons recognized in India are:

  • Cold Weather Season (Winter) December to February
  • Hot Weather Season (Summer) March to May
  • South West Monsoon Season (Rainy) June to September
  • Season of Retreating Monsoon (Autumn) October and November.

# Hot and dry winds called Loo blow during the day in the Hot Weather Season.

South West Monsoon Season:

  • This season is marked by the onset and advance of monsoon.
  • The winds blow from the Bay of Bengal and Arabian Sea towards the land. They carry moisture with them.
  • When these winds strike the mountain barriers, rainfall occurs.

Season of Retreating Monsoons or Autumn:

  • Winds move backward from the mainland to the Bay of Bengal.
  • The southern parts of India, particularly Tamil Nadu and Andhra Pradesh receive rainfall in this season.

Climate: Climate is about the average weather condition, which have been measured over many years.

  • The climate of India has broadly been described as Monsoon type.
  • Due to India’s location in the tropical region, most of the rain is brought by monsoon winds.

INDIA : CLIMATE, VEGETATION AND WILDLIFE

  • The climate of a place is affected by its location, altitude, distance from the sea, and relief.
  • Due to varied climatic conditions, India has a wide range of natural vegetation.

Vegetation of India can be divided into five types. They are:

  • Tropical Evergreen Forests or Tropical Rain Forest: They occur in the areas which receive heavy rainfall. Important trees found in these forests are Mahagony, ebony and rosewood.
  • Tropical Deciduous Forests or Monsoon Forests: Important trees of these forests are sal, teak, peepal, neem and shisham.
  • Thorny bushes: Plants are like Cactus, Khair, Babool and Keekar.
  • Mountain Vegetation: The trees are coniferous having broad bases and conical tops. Important species of trees are the pine, chir and deodar.
  • Mangrove forests: These are grown in the saline water. Example: Sunderbans.

Wildlife:

  • Gir forest in Gujarat is the home of Asiatic lions.
  • Forests of Assam are the home of the elephants and one-horned rhinoceroses.
  • Camels and wild asses are found in the Great Indian desert and the Rann of Kuchch respectively.
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VI NCERT Geo Gist – Motions of the Earth

Rotation:

  • The earth has two types of motions, namely rotation and revolution.
  • Rotation is the movement of the earth on its axis.
  • The movement of the earth around the sun in a fixed path or orbit is called Revolution.
  • The axis of the earth which is an imaginary line, makes an angle of 66 1/2o with its orbital plane. The plane formed by the orbit is known as the orbital plane.
  • The circle that divides the day from night on the globe is called the circle of illumination. This circle does not coincide with the axis.
  • The earth takes about 24 hours to complete on rotation around its axis. The period of rotation is known as the earthday. This is the daily motion of the earth.

What would happen if the earth did not rotate?

The portion of the earth facing the sun would always experience day, thus bringing continuous warmth to the region. The other half would remain in darkness and be freezing cold all the time. Life would not have been possible in such extreme conditions.

Revolution:

  • It takes 365 ¼ days (one year) to revolve around the sun.
  • A year is usually divided into summer, winter, spring and autumn seasons.
  • Seasons change due to the change in the position of the earth around the sun.
  • The longest day and the shortest night at Tropic of Cancer occur on 21st At this time in the Southern Hemisphere all these conditions are reversed. It is winter season there. The nights are longer than the days. This position of the earth is called the Summer Solstice.
  • On 22nd December, the Tropic of Capricorn receives direct rays of the sun as the South Pole tilts towards it. As the sun’s rays fall vertically at the Tropic of Capricorn, a larger portion of the Southern Hemisphere gets light. Therefore, it is summer in the Southern Hemisphere with longer days and shorter nights. The reverse happens in Northern Hemisphere. This position of the earth is called the Winter Solstice.
  • On 21st March and September 23rd, direct rays of the sun fall on the equator. At this position, neither of the pole is tilted towards the sun; so, the whole earth experiences equal days and equal nights. This is called an equinox.

Hence, there are days and nights and changes in the seasons because of the rotation and revolution of the earth respectively.