Tuesday, March 24, 2009

IS GLOBAL WARMING SO SERIOUS?


About2500 Scientists informed in their report to UNO that only eight years left to take remedies from the bad affects of Global warming. About 105 countries agreed on this. Govt of India also considered it serious and discussing in the Parliament about this issue.
Let us see what will happen to India due to this Global warming.
1. Every year sea level in Bay of Bengal is rising by 3.14 mm. This causes inundation of coastal areas and about 70 lakh people are going to loose their houses, paddy and cattle etc.
2. By 2030 about 4/5 of ice in Himalayas is going to melt. Due to this ice water combines with river waters of Ganges and Brhmaputra and about 37% of cultivated land becomes infertile and about a population of 50 crores who are dependent on this will be affected.
3. People in India are dependent on weather mainly monsoon seasons, now due to this Global warming monsoons will not follow their cycles and their period is also reduced. So in India the Hydrological cycle disturbs.
4. If the mean temperature of India increases by 2.5 degrees Celsius then the percentage of paddy yield decreases by 20%and wheat by 41%. Already the mean temperature is increased by 1 degree.
5. The average income of a farmer decreases by 25%. And that of a common man decreases to 1/3 of present income.
6. The coastal areas of Bay of Bengal gets adverse weather effects like increase of day temperatures, unusual heavy rainfalls, storm surges etc.
7. Will it going to happen? Yes, it will, we are already affected by the Global warming: The average temperature of this Globe already increased by 1 degree and it is going to increase by 2 to 4 degrees by the end of this century.
8. The sea level already increased by 15 cm since 100 years.
9. In the last century, the present decade has seen highest temperatures.
10. And lastly all scientists are saying that Ozone holes are increasing in the ozone layer.
11. This is all man made. In the History it is always seen that man is making mistakes and suffering for it. But he can also rectify them.
12. What is the cause of this Global warming, using of Geo oils like petroleum, diesel etc. The usage of these oils is increasing day-by-day, releasing CFC gases that affect the so-called ozone layer.
13. But instead of reducing their usage, scientists are thinking indifferent ways. One of which is to reduce the affect of Sunlight by whitening the deserts so that Sun” s radiation is reflected back. Other is thinking to move the earth towards Mars. Another is thinking to churn the seawater and produce artificial clouding.
14. The above are all eyewash researches only.
15. The only way is to think of other fuels instead of petrol and diesel that will not produce harmful gases. The gases released by vehicles are not only producing this Global warming but becoming health hazards to small children causing Asthma and other heart problems.
16. So concluding Global warming is to be taken serious not only by the Govt. but also by the public and reduce the usage of geofuels and increase the greenery by plantation.
MONSOON DEPRESSIONS/CYCLONES FROM 1997.
17. IN 1997 there were five depressions and one cyclonic storm.
18. In 1998 there were two depressions and two cyclonic storms.
19. In 1999 there were four depressions and no cyclone.
20. In 2000 there were two depressions.
21. In 2001 there was one depression and a cyclone.
22. In 2002 there was no depression or cyclone.
23. In 2003 there were three depressions.
24. In 2004 there were again three depressions.
25. In 2005 there were five depressions and a cyclone.
26. In 2006 there were eight depressions and a cyclone.
2006; IN JUNE only one low pr area. IN JULY A DEEPDEPRESSION. in August one D.D and three depressions a record since 1891. In September one severe cyclonic storm in Arabian sea and two depressions over bay of Bengal and one land depression and the last depression in bay on 28th.

Conclusion

Among all the natural disasters related to water and weather, Tropical cyclones are the only one, which allows two, or three days time for preparedness measures and advance actions to be taken. Over the years, the Indian meteorological Department (IMD) has build up technologies like satellites, radars, computers and telecommunication systems. In the event of an approaching tropical cyclone, IMD informs and warns all the concerned sectors in the government the local population and media, through a variety of communication means. In spite of these efforts, the impact of a tropical cyclone is many times not properly visualized until it is too late to act. A much higher degree of disaster preparedness can be achieved if the destructive potential of the tropical cyclone is fully understood and appropriate actions are initiated.

Regarding Tropical Cyclones hitting the Andhra coast generally the Northern sector of the cyclone affected areas gets more damage due to tidal waves, galewinds and heavy rains. So the concerned state govt should take mitigation measures accordingly. Further the frequency of systems forming in Indian seas is also decreasing during last 50 years.

Even though the climate change is not that alarming but it is changing in most of the places in the world, and everybody knows it is due to Global warming. This can be prevented by using geo-fuels, increase of greenery by plantation and to reduce the production of fluoro-chloro-carbon products which are destroying the well protected ozone layer around the Globe.

The historical constructions like the Sethu are to be protected because they were constructed for the cause of future benefits of mankind and not due to their self interest (Who so ever HE/SHE may be).

STORMS IN OCTOBER MONTH CROSSING ANDHRA COAST



Cyclonic storms and severe cyclonic storms form during October month generally cross the East coast of India. The storms in October month mainly form in South east bay and move into West central bay and then cross Andhra coast. These storms contribute heavy rains to the north of the system. A list of cyclonic storms from 1980, that crossed Andhra coast during October month and their rainfall contributions are as follows. They clearly indicate that Northern sector of the system gets heavy rainfall up to 200 to 300 km North of the center of the system compared to southern sectors where the rainfall amounts are meager.

1. In 1980 a severe cyclonic storm with a core of hurricane winds crossed Andhra coast north of Machilipatnam on 18 Th early morning. From the rainfall amounts in cm it is seen that during the period 17-19 th Srikakulam received 16, Vizianagaram received 17, Visakhapatnam 13, East Godavari 14, West Godavari 12, Krishna 7, Prakasam 7 and Nellore 3. So the northern districts received rainfalls more than 10cm with a maximum of 17 in Vizianagaram district that is about 300 KM from the center of the system.
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3. In 1982 a Severe Cyclonic storm over west central bay weakened into a depression and crossed coast near Kakinada at midnight of 16 Th October. The system weakened very rapidly in its final stage. Exceptionally heavy rainfall occurred to the north of the system with Waltair reporting 37 cm, kalingapatnam 34cm, and yellmanchili 22 cm.

4. In 1982 a severe cyclonic storm crossed South Andhra coast near Sriharikota between 1700 and 1800 hrs UTC of 18 Th. The cumulative rainfall in cm for the period 16-18 th october82 are as follows. Srikakulam 21, Vizianagaram 19, Visakhapatnam 20 East Godavari 4, West Godavari 3, Krishna 3, Guntur 2 Prakasam 2, and Nellore 3. So the district where the system crossed received only 3 cm rainfall where as the districts which are about 300 to 500 km from the center of the system received about 20 cm rainfall.

- 4. In 1983 a Cyclonic storm crossed north of Visakhapatnam around 2000 hrs Utc of 3 rd October. The cumulative rainfall in cm for the period 3 to 5 october are Srikakulam 14, Vizianagaram 17, Visakhapatnaqm 22, East Godavari 11, West Godavari 12, Krishna 8 , Guntur 3 Prakasam 1 and Nellore 0.3.
The place i.e Viskhapatnam where the system crossed the coast received the maximum rainfall of 22 cm and again the northern districts received the 14 and 17 cm rainfall and decreased towards south to an amount less than 1cm

5.In 1985 a Cyclonic storm that was at 16.5 N and 84.5 E at 1200 utc of 10th weakened and close to Visakhapatnam at 0300 utc of 11 th. The cumulative rainfall for the period 10-12 was Srikakulam 6 cm, Vizianagaram 4 cm, Visakhapaatnam 8 cm, East Godavari 11 cm, west Godavari 12cm, Krishna 1 cm Guntur and Prakasam 2 each and Nellore 0.3 cm.

The rainfalls at East and West Godaavri districts indicate that northwest sector of the system received heavy rains when the system was intense and out at the sea. The sharp decrease in rainfall in southern sector from krishnadistrict is clearly seen from the rainfall amounts.

. 6.In 1987 a cyclonic storm crossed north of Ongole between 0100 and 0200 UTC of 16 th. The cumulative rainfall in cm in during the period 15-17 was Srikakulam 22, Vizianagaram 17, Visakhapatnam 18, East Godavari 12, West Godavari 8, Krishna 6, Guntur 7, Prakasam 12, and Nellore 4. The rainfall amounts clearly indicate that Prakasam where the system crossed coast received heavy rainfall and the extreme northern sector i.e Srikakulam vizianagaram and Visakhapatnam received the heavy amounts. Again the neighboring southern district i.e Nellore received considerably low amount.
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7.In 1987 in the month of November a Severe Cyclonic Storm crossed near Machilipatnam
On 13 th. The chief amounts of rainfall recorded at 0830 hrs IST of 13 in cm are as follows. Calingapatnam 10, Sompeta 10, Tekkali 10 (Srikakulam district) Cheepurupalli 10, (Vizianagaram district) Waltair 13, Visakhapatnam (Airport) 11, Yellamanchili 7, Paderu 6, (Visakhapatnam district) Kakinada 9, Prathipapadu 8, Rajhamundry 6 (East Godavaridistrict) Atchanta 11, Koderu 11, Narasapur 11, Bhimavaram 8, Eluru 6, Chintapalli 6, (West Godavari district) Machilipatnam 12, Nandigama 9, Gudivada 9, Avanigedda 10, Vijayawada 7, (Krishna district)Baptla 21, Sattenapalli 12, Tenali 15, (Guntur district) Ongole 10, Addanki 15, Podili 11, (Prakasam district) Kavali 5 (Nellore district). So, even in November, places that are about 300 km from the centre of the storm get heavy rainfalls and gale winds. Visakhapatnam reported about 35 to 45 knot wind from 0900 UTC to 1800 UTC of 12 th when the storm was about 350 km South west of Visakhapatnam

So, concluding that northern sector of the system getting heavy rainfall indicates that these are NE monsoon type. October is the transition month after South West monsoon resides, NE monsoon sets over Andhra coast and Tamilnadu coast. During October the monsoon trough or the equatorial trough comes down and it will be between 10 and 15 degrees latitude. Similarly the upper air trough also will be over ANDHRA AREA UPO 500 mb. The convergence between the easterlies and north lies will be on the northern sector of the system. So the northern sector experiences heavy rainfall like in SW monsoon where the sw sector experiences heavy rainfall. So the forecaster should issue the rainfall and gale winds warning keeping the fact that northern sector gets more adverse weather than the southern sector and accordingly the concerned districts are warned during the month of October.

Monday, March 23, 2009

climate in india

At One time, Climatology consisted of meteorological parameters like precipitation, temperature, cloudiness, humidity, wind etc. Climatic classification was based on a few of these parameters mostly on precipitation and temperature. Later the interest of meteorologists shifted to the fluctuations around the mean state. Before dealing with climatology we should think in terms of different length scales.
Planetary 5000km
Synoptic 1000km
Meso 100km
Micro 1km or less

Sometimes there will be interaction between different scales. All these scales are earth anchored in position and depend on different systems whose time period varies from few days to one year. The main systems include ITCZ, STR, STJ, PJS, etc.
These are largely responsible for the formation of arid, semiarid, wet
and other climatic zones and also for the seasonal changes of weather in each climatic zone.
Now coming to India, India is in tropical region extending into extra tropical region affected by both tropical and extra tropical systems. Monsoon depressions, and cyclones are major tropical systems affecting coastal areas. Where as western disturbances coming from west affect northern part of the country. Lying between the greatest land mass and the warmest sea, shut in by the loftiest mountains, backed by the highest plateaux of the world, India provides the best conditions for a monsoon. India, especially North West India, thus becomes virtually the terminus for the ocean winds from the south, and only from the south in summer and the center of dispersal of land winds in winter. Within a area of varied relief embracing about 3 million square kilometers and extending through 30 degrees latitude there must naturally occur a great variety of climatic types, ranging from continental to marine and from arid to humid; but its almost complete detachment, by virtue of its natural frontiers, from the rest of Asia makes India, as a climatic unit capable of independent treatment
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Further as we are aware that inclination of the earth and revolution around the Sun causes seasons. According to IMD the year is divided into four seasons.

Winter season (Jan and Feb)
Summer season or premonsoon season (March, April and May)
Southwest Monsoon season (June to Sept)
Post Monsoon or Northeast Monsoon season (Oct to Dec)

So, the climate of different parts of India depends on the above four seasons. Generally southern parts of the country experience warm and humid climate and northern parts experience moderate temperature and dry climates. Further the Climate of a place depends on the Altitude of the place, Orography, Land and sea distribution, Ocean currents etc. A place located at a very high altitude would have a climate quite a different from a place just a few meters above sea level. Mountains play an important role in modifying the climate. When humid air ascends from the mountain it can produce, heavy precipitation on the windward side and less rainfall over the lea side. Over India Himalayan mountains are preventing the polar cold air mass entering to India and further contributing heavy rainfall on the southern and eastern side of the Himalayas. This is the reason for heavy rains in the northeast part of the country.

Seasonal temperature differences between continents and oceans produce temperature variations in pressure, rainfall, wind etc. So marine course gets moderate temperature climate whereas the inner continent gets extreme temperature. In India the northern part is located up by the land and so gets extreme minimum and maximum temperature where as the southern part surrounded by the sea gets moderate temperature.
Ocean currents are produced by the winds over the sea surface and horizontal variations of density of seawater. These currents carry tropical warm waters towards the eastern side of the country in low latitudes and temperate water towards the western side. This causes warming up seawater and instability in the atmosphere in the eastern side.
As already said the climate for a year depends on the four seasons described above.

WINTER SEASON

During winter the land will be much colder than the sea areas . So a high pressure area forms over land in the northern side and low pressure on the sea on the southern side of the country. During this season the sun is in the southern hemisphere. So the equatorial trough lies between the equator and 10 degree south. On sea level chart a trough runs along the west coast and a ridge along the east coast. The winds blow from the land to sea. In the upper atmosphere an anticyclone lies along the center part of the country up to 1.5 Kms. and strong westerlies in the higher levels reaching up to 100 knots over J& K.
Lowest temperatures are recorded over North West India causing cold wave. Western disturbance is the most important weather system during this season. They are the low pressure systems coming from west moving eastwards across northern part of the country causing thunder storms and hailstorms. Western Himalayas experience snowfalls. An average two to three disturbances pass on every month and the WD last for 4 to 5 days. In the rear of the WD radiation fog is observed in the northern part and advection fog in the costal areas. Cold waves are common in this season in the north extending into peninsular India. The minimum temperature fall up to 6to 7 degree causing cold wave and some times 8 to 10 degrees fall causing severe cold wave.


HOT WEATHER OR SUMMER OR PREMONSOON SEASON.
This season is characterized by extreme high temperature, severe thunderstorm, dust storms/sand storms and cyclones. There will be a pressure difference caused by intense heating between land and sea and as a result winds blow from sea to land. A trough of low pressure lies over central parts of India and two anticyclones in the lower troposphere are seen over Bay and Arabian sea. In the upper troposphere strong westerlies are seen over north India.
The area of highest temperature shifts slowly towards northwards during may and June and northwest India becomes the hottest. The mean maximum temperatures will be more than 40 degrees Celsius in the northern and central parts of the country.
Severe thunderstorms are the major weather systems during this season. NE India experiences a high frequency of thunderstorms during this season and they are called NORWESTERS or KALBAISHAKIS. Where as northwest India experiences dust storms, which are locally known as Andhis. Rajasthan, Punjab, Harayana, Gujarat etc are more vulnerable for dust storms. In the desert areas sand storms cause havoc making the visibility to few meters. There will be thunderstorm activity throughout the country. These thunderstorms are accompanied with squally winds and heavy rain
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Heat waves are common when the maximum temperature raises by 6to 7 degrees Celsius and in North India severe heat waves occur when the temperature rises by more than 7 degrees. They last for a bout a week
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Cyclones are also common during this season. They generally form in the Bay of Bengal and affect the east coast of India.

SOUTHWEST MONSOON SEASON.

This is the most important season for India contributing about 70% of annual rainfall. An intense low-pressure area forms over Pakistan and adjoining Rajasthan and a trough from this extends up to head bay. This is called Monsoon trough it extends up to higher levels tilting southwards with height. Even though the Sun is in the northern hemisphere, due to this Monsoon, most parts of the country is covered with clouds and the temperatures starts falling, even the warmer areas in Rajasthan gets cooled by the end of July.
The normal onset of sw monsoon over Kerala is first June; there afterwards it covers entire country by July 15th.The main weather system during this season is formation of monsoon depression. Generally they form in the head bay and move along the monsoon trough giving torrential rains across its track. The life period of a monsoon depression is about 5 days. About 6 to7 depressions form during monsoon season. When the monsoon is active, mid trophospheric circulations form over Gujarat giving heavy rains over Gujarat, Rajasthan and adjoining areas.
There is one period when the monsoon trough shifts to the foot of the Himalayas This shifting leads to significant reduction of rainfall over most parts of India and this situation is called Break Monsoon. During this period Tamilnadu gets rains, which was shadowed by southwest monsoon.
So during sw monsoon all parts of the country get rainfall by some phenomena or other. ` By September 15 SwMonsoon starts withdrawing from NW India and by 30 th September monsoon season ends.

POST MONSOON OR NORTHEAST MONSOON SEASON.

This is the principal rainy season for Tamilnadu , coastal Andhrapradesh and Rayalaseema. When the Sw monsoon with drew from entire country, North east monsoon sets over the southern part of the country. Formation of Depressions and cyclones over Bay of Bengal is the major weather phenomena during this season
Cyclones initially form as low pressure areas over Bay of Bengal or ARABIAN SEA and starts intensifying into depressions, cyclones etc. The cyclones starts moving ina northwesterly direction further intensify into severe cyclonic storms and super cyclones and hit the east coast of India The most affected areas are Tamilnadu, coastal andhrapradesh, orissa and west Bengal. The cyclones in Arabian Sea affect Maharasatra and Gujarat coasts; A cyclone is accompanied with heavy rains gale winds and tidal waves. The tidal waves cause storm surge at the point where they strike the coast. Human loss, structural damage, loss of cattle etc are the main damages caused by a cyclone. Of course by proper warning the loss of life can be reduced.

Reviewing broadly the rainfall of India, it is noticeable that while relief rains give the heaviest falls, it is the monsoon and cyclonic type which, on account of its more even distribution, is of greater economic value as for example, in the Gangetic plain and the deccan plateau during monsoon season, and the Punjab and NWIndia during Cold season. At no time of the year is India entirely without rain. Even though Jan and Feb. are driest months northwest India enjoys rain from westerndistrurbances. March, April and May being thunderstorm season except NW India other party gets rainfall and especially NE India gets about 30% of its annual rainfall. June to October all parts gets monsoon rainfall and Nov and Dec southern parts gets rains due to cyclones and western disturbances activity starts in northern parts.

However the climate is changing at different places due to urbanization, cutting of forests, release of harmful gases etc. Further the Global phenomena, like El Nino, Global warming etc are also affecting the seasonal weather phenomena like Monsoons, winter at different places. This is causing unprecendential rains, floods and droughts in some areas during a year. Let us hope that Nature protects herself and we Indians help in protecting Beautiful Climate of India and make it Heaven in the World.