vikrant. ppt

Kurukshetra University, KurukshetraDepartment of Environment Science

Submitted BY :-Name : Vikrant saini Class : MSC(P)Roll no . 4

Submitted To :-Prof. Smita chaudharyDirector of Department Environment science

Contents

• Definition

• Cause

• Indian Monsoons

• Types of Monsoons

• El Nino and Effects

• La Nina and Effects

• Conclusion

Monsoons

• Monsoon is term derived from the Arabic word “Mausim”, meaning season. It was first used by Arabic navigators to describe the seasonal winds of Arabian sea.

• These winds blow from the north-east for one half of the year and for the south-west of other half.

Cause•Monsoons occur due to changes in atmospheric pressure which are caused by different rates of heating and cooling of continents and oceans.• Monsoons occur every year in many countries around the world other than South Asia - northern Australia, Africa, South America and the US are also affected.

•The Indian monsoons :

•India’s climate is dominated by monsoon.•The term technically describes seasonal reversals of wind direction caused by temperature differences between land and sea breeze ,creating zones high and low pressure over land in different seasons.

Types of monsoons :Types of monsoons

•South west monsoons

•North east monsoons

South west monsoons :-

The South –West (summer) monsoon has warm

winds blowing from Indian Ocean. Its span is June to

September, with 75 % of the annual rainfall in India. It

varies from 10 cm in western Rajasthan to over 900 cm inMeghalaya.

North east monsoons :-

North- East (winter) monsoon is characterized

by a dry continental air mass blowing from the vast Siberian high pressure area from December to March. The rainfall includes snowfall during winter monsoon which is of the order of 1000 km2 in India. This is also known as Retreating monsoon.

Map : 17th June 2013

• El Nino refers to the large-scale ocean-atmosphere climate phenomenon linked to a periodic warming of at least 0.5°C in sea-surface temperatures across the central and east-central equatorial Pacific.

El Nino:

Normal conditions EL Nina conditions

Normal conditions :-

EL Nino effect :Weak trade winds and weak upwelling cause warm water off the coast of S. America.

Effect of EL Nino :-

1.Dry conditions:-

2. Flood conditions :-

La Nina:- La Nina refers to the periodic cooling normal by 3–5 °C of

ocean surface temperatures in the central and east-central equatorial Pacific.

Normal conditions La Nina conditions

La Nina :-

Conclusion

• A monsoon is a seasonal shift in the prevailing wind direction, that usually brings with it a different kind of weather.

• Monsoons are large-scale sea breezes .

• El Niño and La Niña are naturally occurring phenomena that result from interactions between the ocean surface and the atmosphere over the tropical Pacific.

References

Contents – Monsoonshttp://www.monsoons.com

Contents - El Niño http://www.msc-smc.ec.gc.ca/education/elnino/index

El Niño/La Niña Updatehttp://www.wmo.ch/nino/updat.html#intro

Any Question ?