Types of Winds

Winds:

The Wind is the movement of air caused by the uneven heating of the Earth by the Sun.

Sometimes the wind blows gently, refreshing us. At other times, it blows strongly creating storms that cause widespread damages.

We need measurements of two quantities: direction and speed, to give a description of the wind.

Types of Winds:

Trade Winds:

A wind blowing steadily towards the equator from the north-east in the northern hemisphere or the southeast in the southern hemisphere, especially at sea.

They blow from the Subtropical High-Pressure Belt to the Equatorial Low-Pressure Belt in the tropics between 30°. North and 30° South latitudes.

They blow as the N.E. Trades in the Northern Hemisphere and as the S.E. Trades in the Southern Hemisphere.

The name "Trade" is derived from a nautical expression "to blow tread" meaning to blow along a regular path or "tread".

Westerlies:

They blow from the Sub-tropical high-Pressure Belt to the Sub-polar low-Pressure Belt in the temperate latitudes between 30° and 60°, on either side of the Equator.

They are more constant and stronger in the Southern Hemisphere because there are no large landmasses to interrupt them.

In places, they become so strong that these winds are known as the Roaring Forties or the Brave West Winds and the Furious Fifties.

The belts of the Westerlies move north and south following the Sun's movement. These are known as Westerlies because they blow out of the west.

 Polar Winds:

They blow from the Polar High-Pressure Belt to the Subpolar Low-Pressure Belt between latitudes 60° and the poles on both sides of the Equator.

They winds blow from the east to form the Polar Easterlies.

They are more regular in the Southern Hemisphere.

Polar winds are extremely cold and dry.

Climatic Winds or Periodic Winds:

These winds change their direction along with a change in time or change in climate.

Land and sea breezes and the Monsoon winds are typical examples of periodic winds.

Monosoon Winds:

Monsoon winds are seasonal winds characterized by a complete reversal in their direction from one season to another.

They blow from the sea to the land in summer.

They blow from the land to the sea in winter.

Forests:

They are of the following types:

Tropical Evergreen Rain Forests:
Such forests are found in the equatorial and the tropical regions with more than 200 cm annual rainfall. The leaves of trees in such forests are very wide. Ex-Red wood, palm etc.

Tropical Semi-Deciduous Forests:
Such forests receive rainfall less than 150 cm. Sangwan, saal, bamboo etc. are found in such forests.

Temperate mixed Forests:
Such forests are a mixture of trees and shrubs. Corks, Oak etc. are the major trees of these forests.

Coniferous Forests or Taiga:
These are evergreen forests. The trees, in these forests, have a straight trunk, conical shape with relatively short branches and small needle-like leaves. Example-Pine, Fir etc.

Tundra Forests:
Such forests are covered with snow. Only Mosses, a few sledges and Lichens grow here in the summers. This type of vegetation is chiefly confined to the northern hemisphere (e.g. in Eurasia, North America, and Greenland Coast).

Mountainous Forests: Vegetation varies according to altitude.

Pastures (or Grasslands):

They can be divided into two types:

Tropical Pastures and

Temperate Pastures

Tropical Pastures: They have different names in different countries.

Savanna in Africa,

Campos in Brazil,

Lanos in Venezuela and Columbia.

Temperate Pastures:

They are known by the following names-

Prairies in USA and Canada,

Pampas in Argentina,

Veld in South Africa,

Rangelands or Downs in Australia and Newzealand

Steppes in Eurasia (Ukraine, Russia).

Physical Divisions of the Indian Subcontinent

A chain of high mountains radiates out from thePamir Knot which lies just in the north of India.

In these mountains, the Hindukush, the Sulaiman, and the Kirthar in the East and the Himalayas in the west separate the Indian subcontinent from rest of Asia.

Indian subcontinent can be divided into following physical divisions:

The Great Mountain Wall of the North

The Great Northern Plains

The Great Peninsular Plateau

The Coastal Plains

The Great Indian Desert

The Island Groups.

The Great Mountain wall of the North:

The Himalayas, the highest mountain wall of the world, are situated on the northern boundary of India like an arc.

From west to east the Himalayas are 2500 km long. The average breadth of the Himalayas is between 250 km to 400 km.

Mount Everest, the highest peak in the word, lies in these mountains in Nepal.

Division of the Himalayas

The Himalayas consist of three parallel mountain ranges:

(i) The Greater Himalayas

(ii) The Lesser Himalayas and

(iii) The Outer Himalayas.

The Greater Himalayas (or Himadri)

This is the loftiest of the three ranges of Himalayas.

Mount Everest lies in this range.

These snow-covered mountains give birth to many glaciers.

The Ganga originates from this glacier.

The Leasser Himalayas (for the Himachal Himalayas):

South of the Greater Himalayas, the range also lies parallel to it from west to east.

This ranges 60 to 80 km wide and its average height ranges between 3500 to 4500 meters.

Tourist centers like Shimla, Mussoorie, and Nainitalare situated in this range

The Outer Himalayas (or Shiwaliks):

This is the southernmost and the third parallel range of the Himalayas with an average height of 900 to 1200 meters.

Its breadth is only 10 to 15 km. Shivalik range is broader in the west.

Heights of Major Mountain Peaks in India

*represents the mountains situated in PAK.

The Great Nothern Plains:

The Northern plains are divided into three sub-divisions. These are the Punjab and Haryana plains. The Ganga plains and the Brahmaputra valley.

The Ganga plains form the largest lowland drained by thy Ganga and its tributaries.

The Yamuna is the most important tributary of the Ganga.

The Ghaghara, the Gandak, the Kosi and the Tista are other tributaries of the Ganga.

The Sone and the Damodar are tributaries of the Ganga while the Chambal and the Betwa are tributaries of the Yamuna from the peninsular plateau.

The Ganga plain has an extremely gentle slope. Parts of the plain are subject to floods in the rainy season. In the lower course, the Ganga divides itself into tributaries to form a large delta along with the Brahmaputra.

The Punjab and Haryana plains represent a part of the Indus basin.

A low watershed separates these plains from the Ganga plains.

The Great Pensinsular Plateau:

Anamudi or Anaimudi (2695 m) is the highest peak of the Peninsula.

The Deccan plateau includes the area to the south of the Vindhyas.

The western edge of the plateau rises steeply from the Arabian Sea to form the Western Ghats (which includes the Shahydri).

The Deccan plateau slopes gently towards the east. The surface of the plateau is dissected into a rolling upland by a number of rivers.

The elevation ranges from 300 to 900 meters.

The eastern edge of the plateau is known as theEastern Ghats.

The north-western region of the Deccan plateau is covered by nearly horizontal sheets of lava.

This region is called 'Deccan trap region'. The Deccan plateau is drained by many long east flowing rivers.

These rivers originate in the Western Ghats, flow towards the east and enter the Bay of Bengal.

The Godavari, the Mahanadi, the Krishna and the Cauvery are the major rivers that have built deltas along the coast.

The Narmada and the Tapti rivers are west flowing.

Both the rivers enter the Arabian Sea along the Gujarat coast.

These rivers do not have deltas.

Major Plateaus: Marwar Upland, Central Highland, Bundelkhand, Malwa Plateau, Baghelhand, Chhotanagpur Plateau (Hazaribagh Plateau, Ranchi Plateau, and Raj Mahal Hills), Meghalaya Plateau, Deccan Plateau, Maharashtra Plateau, Karnataka Plateau, Telengana Plateau, Chhatisgarh Plain.

The Coastal Plains

Narrow strips of flat land on eastern and western coasts are known as the East Coastal Plain and theWest Coastal Plain respectively.

The West Coastal Plain

This plain which lies between the Arabian Sea and the Western Ghats spreads from Gujarat in the north to Kanyakumari in the south.

It is broader in the north and narrower in the south. This uneven plain has been dissected by many fast-flowing rivers.

Its northern part from Gujarat to Goa is called Konkan, while southern part from Goa to Kanyakumari is known as Malabar. Several lagoons (salt water lakes separated from the main sea by sandbars and spits) are found on the coastal plain.

Important ports developed on its coast from north to south are Kandla, Mumbai, New Jawahar Port Mumbai, Marmagao, Mangalore, and Cochin.

The East Coastal Plain:

This broader coastal plain spreads along the Bay of Bengal from Odisha in the north to Kanyakumari in the south.

Its northern part is known as Northern Circar plainsand the southern part is called Coromandel Coast.Rivers like Mahanadi, Godavari, Krishna and Cauvery form deltas on this plain.

This coast is famous for rice cultivation.

A large number of lagoons are also found here.

Chilka and Pulicat lakes are fine examples of lagoons on our east coast.

The Great Indian Desert:

It lies to the west of the Aravali range.

It extends over major part of Rajasthan and Sindhi in Pakistan.

This desert does not get much rain as the Aravali range run parallel to the south-western monsoon winds.

It is in the rain shadow area of the Bay of Bengal current.

Lake Sambhar is found here.

The Island Groups

Lakshadweep is a group of 36 coral islands in the Arabian Sea.

It is located 300 km to the west of the coast of Kerala.

Andaman and Nicobar Island are a group of about 324 islands.

Most of these islands are uninhabited.

Andaman and Nicobar islands are separated by the Ten Degree Channel because 10°N latitude passes through this place.