Monday, July 20, 2009
Latest satellite pic
Shows heavy rainfall already over Orissa is still continuing. This system is driving in more moisture into Kerala and south-coastal karnataka.
Here's the forecast from IMD::
The well marked low pressure area over northwest Bay of Bengal and neighbourhood concentrated into a depression and lay centred at 0830 hours IST of today, the 20th July 2009 near Lat 21.0 ° N and Long 88.5° E, about 120 Km southeast of Digha and 160 Km east-southeast of Balasore. The system is likely to intensify further and move in a west-northwesterly direction and cross north Orissa-West Bengal coast between Balasore and Digha today, the 20th July 2009 evening.
According to the MET Office, over 100 mm of rain has been recorded in Karachi while around 90 per cent of the area remains without electricity for more than thirty hours. The heavy rain and gusty winds wrought havoc on Karachi's infrastructure. Over 150 people were injured and the death toll from rain-related accidents in different areas of the city has risen to 28. Most of the victims were women and children living in shanties. Here is a glimpse of some of the worst hit areas courtesy Dawn
The southwest monsoon remained erratic in North India today with several places receiving moderate to heavy showers while the rest craving for an incessant spell of rain.
Showers drenched parts of Rajasthan, Punjab and Haryana where the monsoon showed signs of gaining momentum while it was subdued in the national capital and some other places in the belt.
Despite rains, temperatures settled above normal at many places in Punjab and Haryana with high humidity levels, which fluctuated between 85 and 92 per cent, adding to discomfiture of the denizens.
Hisar in Haryana reeled at a high of 41.4 degree Celsius, four notches above normal, as Amritsar in Punjab too endured a hot and humid day with the maximum settling at 38.8 degrees.
As many as 32 mm of rains fell on the Union Territory of Chandigarh, 22.2 mm on Patiala, 10.
Met department is not the only one predicting weather in India. Forecasts are now sold by businesses to businesses
At the peak of summer weathermen in Pune sat down to predict when the monsoon will hit India and how much rainfall it will bring. They fed data into forecast models, and out came the result: rainfall will be 96 per cent of the normal, they announced on April 17. But in June the country received only 57 per cent of the normal rainfall for the month.
The government-run India Meteorological Department (imd) in its internal communication had said the June rainfall would be considerably less than normal, yet neither imd nor farmers across the country expected it to be so low. "The last time such a low rainfall was recorded in June was in 1926," said D S Pai, scientist at imd Pune who is in charge of forecasts.
On June 24, imd modified its forecast, saying the monsoon will be 93 per cent of the normal. Its scientists said their earlier forecast followed statistical probability that relies on historical data, not the prevailing weather conditions, to predict the trend. They did suspect that El Nino, a periodic weather anomaly, and heavy snowing in Eurasia would play spoilsport. But, according to Pai, two things happened in May that took them by surprise: Aila cyclone hit West Bengal and western disturbance hit north India. Aila took away a large part of the moisture in the air and western disturbance brought drizzle cooling down the northern parts of the country. This weakened the monsoon, said the scientist.
Is weather forecast on the basis of historical data relevant any longer? Research shows trends of decreasing rainfall in June and July (see 'Monsoon earlyburly', Down to Earth, May 16-31, 2009). "We try to take the results from 10 dynamical forecast models, and often each model gives a different version of the weather," said Pai. "Unsure of the results we settle for the age old statistical model." Dynamical models take into account weather conditions like cloud movement and humidity.
Several imd scientists, who do not want to be named, say dynamical models are not reliable because they are not customized to Indian conditions. These models also need regular updates, which require research. imd scientists complained that though such research is happening in organizations like the National Centre for Medium Range Forecasting, iits, Indian Institute of Science and the Indian Institute of Tropical Meteorology, there is not enough interaction between the researchers and forecasters.
"There is almost a caste-like division among meteorological researchers in other organizations and forecasters in imd. So much so they do not publish in same journals," said an imd scientist. "Interaction is limited to seminars."
imd is not very happy about its seasonal predictions meant for the government to formulate its agricultural strategies. But it is confident about its medium- and short-range forecasts given five days and one day ahead respectively.
Enter the private forecaster
Knowing which way the wind blows-or does not-is not left to imd any more. Over the past six years a clutch of companies in India has entered the business of predicting and recording the weather every day, every hour, every 10 minutes. It depends on how frequently the client wants the data. These companies cater to the specialized needs of increasingly competitive sectors like power.
On July 22, 2009, the Moon's shadow passes over several large cities in Cina - including Shanghai. Red labels indicate the duration of totality, the Sun's altitude in the sky, and the Universal Time of mideclipse.
Prospects for clear skies along the eclipse path are chancy. Data are derived from NOAA's International Satellite Cloud Climatology Project. Click on the graph for a larger view showing the entire centerline.
For the second time in a year, a total eclipse of the Sun is about to cross China. But unlike the Moon's hard-to-reach shadow path last August, the celestial spectacle on July 22, 2009, will darken major cities, densely populated countryside, and a vast expanse of tropical ocean. And the eclipse itself will be a monster, with totality lasting more than 6.6 minutes at maximum. That makes this the longest totality until 2132.
A total solar eclipse occurs once every year or two on average, but each is visible only from a narrow track covering less than 1% of Earth's surface. The eclipse of August 1, 2008, was visible only from parts of the Arctic, Siberia, and central Asia. Nevertheless, thousands of enthusiasts traveled by land, air, and polar icebreaker for the chance to bask briefly in the silvery twilight glow of the Sun's corona.
The main reason why this year's totality lasts so long is because the eclipse starts just a few hours after the Moon reaches perigee. At such a close distance, the Moon appears fully 8% larger than the Sun and casts a broader than usual shadow. At the point of greatest eclipse in the western Pacific, the path of totality is 258 km (161 miles) wide.
The umbra (dark central portion) of the lunar shadow first touches Earth at sunrise at 00:53 Universal Time in the Gulf of Khambhat off western India. The shadow takes just 8 minutes to cross India before spilling into northern Bangladesh and easternmost Nepal. A minute later the umbra engulfs most of Bhutan, while the eclipse duration on the central line crosses the 4-minute mark. The Sun's altitude is 21°. The shadow then crosses northern Burma, a corner of Tibet, and China's Yunnan province. Passing through the middle of Sichuan province, the eclipse track darkens the capital city of Chengdu (2 million inhabitants, 3.3 minutes of totality), Chongqing (4.1 million, 4 minutes), and Wuhan (9.7 million, 5.5 minutes). Traveling nearly due east, the shadow track encompasses the meandering course of the Yangtze River.
Near the Pacific coast, Hangzhou's 4 million citizens experience a total eclipse lasting 5.3 minutes. The Sun's altitude is now 55°. A minute later Shanghai, China's largest city with 20 million people, plunges into totality for 5 minutes, though it is well north of the central line. This may be the most people that have ever been in the Moon's shadow at once.
As it moves out over the East China Sea, the umbra sweeps over Japan's Ryukyu Islands, then Iwo Jima and Kitaio Jima, before curving southeast across the Pacific. The instant of greatest eclipse occurs at 2:35:19 UT, when totality lasts longest: 6 minutes 39 seconds. This happens over open ocean with no land in sight.
The second half of the eclipse path crosses nothing but ocean and a few tiny islands and coral atolls among the Marshall Islands and Kiribati. The total eclipse finally ends at 4:18 UT, at sunset about 1,000 km northwest of Tahiti. The Moon's shadow lifts off Earth and returns to space, after covering 0.7% of Earth's surface in 3.4 hours.
Monsoon climates and tropical breezes do not bode well for this eclipse in India and China. Along the entire track the season is humid, with frequent clouds and rain. But in some spots the statistics tilt just barely to the good side of 50-50. The dullest skies are on the slopes of the Himalayas, where, at Guwahati for instance, the chance of clouds exceeds 85%. Prospects improve in China: around 55% average cloud cover in July. Shanghai shows an average of 54% sunny.
Pollution in China will be a factor to consider for those who want to view or photograph the outer fringes of the corona. On sunny days the endemic brown haze is much less visible than in poorer weather; blue sky shines through. If skies are clear, or nearly so, even Shanghai's pollution is unlikely to affect the spectacle. Wuhan offers cleaner skies at the expense of a few percentage points in the cloudiness odds and seconds in eclipse duration.
Cloud cover along the track reaches its minimum near Iwo Jima. Ships may be able to find a hole in the clouds, because most weather systems are relatively small and can be dodged with a little planning.
But not typhoons. July is the middle of typhoon season, and the likelihood of one in the eclipse track between Japan and the Philippines is probably close to 10%.
Future Total Eclipses
On July 11, 2010, this part of the world will be favored with its third total solar eclipse in as many years. The track is almost entirely over the South Pacific. Easter Island and southern Chile (at sunset) offer the only landfalls. And the South Pacific also hosts the next one, on November 13, 2012.
A total solar eclipse won't cross the Americas until August 21, 2017, when the Moon's umbra will sweep from Oregon to South Carolina