Geography Notes - for Competitive Exams

Part - 3

Valley winds are also called as anabatic winds.

Mountain winds are also called as katabatic winds or drainage winds.

Below is the list of various Local Winds and their names in those regions:

Bora (north Adriatic coast)

Mistral (southern France)

Santa Ana (California)

Blizzards (Antarctic region)

Cape Doctor (dry south-easterly wind that blows on the South African coast in summer)

Chinook also called as "snow eater" (Rocky Mountains, a mountain range in the western North America)

Elephanta (It is a strong southerly or south-easterly wind which blows on the Malabar coast of India during the months of September and October and marks the end of the southwest monsoon.)

föhn wind or foehn wind (Central Europe)

Fremantle Doctor (afternoon sea breeze from the Indian Ocean which cools Perth, Western Australia during summer)

Punas (Andes [world's longest continental mountain range] along the western coast in South America )

Sirocco (this is a hot dust laden wind of Saharan origin blowing eastwards from Sahara across the Mediterranean)

Solano (wind of Saharan origin blowing from Sahara towards the Iberian Peninsula). Iberian Peninsula is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar.

Harmattan (a relatively cooler dry wind blowing over Sahara in winter season).

Loo (A local hot wind of desert origin blows towards east across the northern plain of India in summer season. This dry hot wind raises temperature significantly in the Ganga Valley up to as far as Bihar).

Cyclones and anticyclones are two special pressure and wind systems. They are also called as variable winds.

A cyclone is a system of very low pressure in the centre surrounded by increasingly high pressure outwards. In a cyclone, the winds blow in a circular manner in a clockwise direction in the southern hemisphere and in an anticlockwise direction in the northern hemisphere.

Cyclones develop in both tropical and temperate regions and accordingly they are categorised as tropical cyclones and temperate cyclones.

Tropical cyclones are very intense and cause great loss to life and property in coastal areas. They are known as cyclones in the Indian Ocean, hurricanes in the West Indies, typhoons in the China Sea and willy-willies in northwest Australia. They are also called depressions.

The winds in a cyclone blow in a circular manner and the flow of air in them is convergent. Consequently, the air rises in the central part and it results in heavy rainfall. The eye is found only in tropical cyclones.

A Tornado is a very strong tropical cyclone of a smaller size. They are specially feared in the Mississippi Valley in the USA and here they are called twisters.

The temperate cyclones develop in the mid latitude regions and the convergence of air masses with contrasting thermal characteristics gives rise to development of these cyclones. Unlike the tropical cyclones, the temperate cyclones do not have an eye.

Anticyclones are the centres of high pressure and they are the opposite of cyclones in all respects. They are centres of high pressure with gentle outward flow of air. The air circulation is clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere. The high pressure belts in the polar areas and the subtropical regions are the important anticyclonic areas. Anticyclones involve a divergent flow of air from an area of high pressure.