WEATHER, CLIMATE AND RAINMAKING IN CHINA

WEATHER IN CHINA

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Summer weather scene
Before the Western Han dynasty (206 B.C. to A.D. 8) the climate in northern China was warmer than it is now and better for raising crops. The Chinese began using weather cocks and vanes very early and were probably the pioneers of wind direction devices. At least as early as the first century B.C., the Chinese recorded "wind seasons," and used kites to record the speed and direction of the 24 seasonal winds.

"When the weather is unusual people do unusual things," goes a Chinese proverb. During unusually mild winters in Beijing weather forecasters sometimes say cold weather is on the way to prevent the proverb from becoming true.

In December 2007, the Chinese government declared that weather forecasts were “state secrets” and said it would clamp down on illegal weather acquisition by foreigners. Violators included an illegal weather station set up by a Japanese company near a power station and a weather observation post near the Olympics yachting venue in Qingdao, which also happened to be near a military harbor.

Chinese meteorologists go about their jobs in a very no nonsense way. An Australian weatherman known for his comic, lighthearted broadcasts told the Los Angeles Times that some Chinese weatherman took offense to his style. “The Chinese take their weather seriously,” he said, “They wanted to know how I could joke about a topic that was likely to kill people.”

Good Websites and Sources: China Meteorological Administration cma.gov.cn ; China.org Weather Click Map weather.china.org.cn ; Weather in China Weather in China Weather Channel Weather Channel ;World Climate World Climate ; Accuweather Accuweather ; Links in this Website: LAND AND GEOGRAPHY OF CHINA Factsanddetails.com/China ; WEATHER IN CHINA Factsanddetails.com/China ; TYPHOONS IN CHINA Factsanddetails.com/China ; SAND, DUST, RAIN AND ICE STORMS IN CHINA Factsanddetails.com/China

Climate in China

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Winter weather scene
China is a big country and the climate varies greatly from region to region. There are places with bitterly cold winters as well as ones with scorching summers and everything in between. Beijing and Shanghai and most of China are very hot and humid in the summer; climate differences are more variable in the winter.

Most of China is in the northern temperate zone. There are complex climatic patterns ranging from the cold-temperate north to the tropical south, with subarctic-like temperatures in the Himalaya Mountains, resulting in a temperature difference of some 40 degrees C from north to south. Temperatures range from –30 degrees C in the north in January to 28 degrees C in the south in July. Annual precipitation varies significantly from region to region, with a high of 1,500 millimeters annually along the southeastern coast and a low of fewer than 50 millimeters in the northwest. There is an alternating wet monsoon in the summer and a dry monsoon in winter. North China and southward are affected by the seasonal cold, dry winds from Siberia and the Mongolia Plateau between September/October and March/April. Summer monsoon winds bring warm and wet currents into South China and northward.

Generally, southern China is relatively wet and northern China is largely dry. Rains tend to fall heaviest near the coasts and in the south and where mountains lift clouds pushed in by southeastern winds. South of the Yangtze River rainfall generally varies between 40 and 75 inches a year. North of the Yangtze rains diminish from 25 inches to 10 inches as one travels north. Rain also diminishes towards the west. In the Gobi Desert in Inner Mongolia and the Tarim Basin in Xinjiang the annual rainfall is less than four inches in many places.

The country's north is prone to droughts, while the south is often flooded. Much of the country's farming still relies on rainfall as many of its communities have a poor irrigation system. The prevailing winds blow across southern China from the southeast. Further north they blow in from the west. Cold air pours down from Siberia in the winter. Warm air comes up from Southeast Asia and the South China Sea in the summer. There are often vicious storms, heavy rains, floods and landslides in the early summer.

Seasonal monsoon winds do not influence China as much as other Asian countries. However the early summer is the peak rainy season in much of China. Seasonal rain fall is often unpredictable, resulting in droughts and floods. Cyclonic storms sometimes approach from Europe. Typhoons strike from time to time, particularly along the southeast coast, in late summer and early fall.

Climate in Southern China

Southern China is a semitropical region with lots of rain, a mild winter (December, January, February), and a hot and humid summer that extends from May to September. The best times to visit are in the fall (October, November) and to a lesser extent in the spring (March, April). The spring is often hazy and rainy, whereas the fall often features clear blue skies with puffy clouds.

The temperatures are generally cooler in the highlands and along the coast. In the summer, the humidity is high, often 90 percent or more, and high temperatures are usually around 90̊F. The temperatures can sometimes drop into the 40s at night in the winter, spring and autumn. Snow falls on the higher mountains.

Southern China is affected most by the monsoon season, which is known to Chinese as the "plum rain season" and is dominated by the Bai-u front. In most places the monsoon season extends from June to September . In some places it begin in May. The Bai-u front brings seasonally heavy rains in June and July. The typhoon season is from July to October. The typhoons that strike southern China come in from the Pacific and South China Sea and are usually characterized more by their heavy rains than high winds.

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Precipitation map

Climate in Central and Northern China

Central and Northern China have four seasons, and the climate is comparable to that of the eastern United States, with the lengths and intensity of the winters and summers varying with the latitude and proximity to the sea. Spring is pleasant, sunny and mild. Summer, arriving in June and often accompanied by month-long rainy season, is characterized by hot, humid weather. The winters tend to be cold and dry. There is snow in many places.

The fall is the nicest time of the year in northern China. The days are often clear; the air is brisk and bracing; the temperatures are cool and there are pretty autumn colors. The spring---especially in Inner Mongolia, Gansu and Shanxi and areas upwind from Beijing---is often very windy, with some intense dust storms that fill the air with chocking grit and turn the sky orange.

Climate in Northwest China and Tibet

Northwest China is very dry, with many places receiving less than four inches of rain a year. Many of the towns and cities have grown up around oases. The summers tend to be scorching and dry with chilly nights and daytime high temperatures that often exceed 110̊F. In some ways the summers are more bearable in the northwest China than elsewhere in China because the humidity is low and the early mornings are relatively cool. The winters are bitterly cold with temperatures often dropping below 0̊F. Spring and autumn are relatively short but pleasant except when fierce dust storms blow up in the spring.

Tibet has a harsh climate. The temperatures frequently drop below minus 30̊F in the winter and rise above 100̊F in the summer, with temperature sometimes fluctuating 80 ̊F in a single day. But generally Tibet is cool or cold and people walk around bundled up in many layers of clothes. It is no surprise that many Tibetans believe that hell is a bitterly cold place not an inferno.

There is very little water in Tibet. Snow frequently falls but rarely accumulates, and the climate is so dry that grain can be stored for 50 years. The extremes of hot and cold, coupled with the thin air and high altitude sunshine, are enough to break granite mountains into sand, and generate fierce winds, stinging hailstorms, and blinding dust storms.

Rain Making and Man-Made Weather in China

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Cloud seeding
China is the world’s leader in artificial rain making. To induce more rain between April and June, when much of China suffers from drought, scientists use aircraft, rockets, artillery and even land-based furnaces to propel small amounts of silver iodine or liquid nitrogen into certain types of moisture-laden clouds which produce crystals that turn into rain as they fall into warmer areas below. Depending on the type of cloud, dry ice and salt can also be added to enhance the effort. Rain-making doesn’t come without its costs. Occasionally villagers complain of rain-inducing missiles crashing through the roofs of their homes.

How Cloud Seeding Works: 1) Silver iodide is fired into cloud using flares on planes or from the ground. 2) Water droplets then attach to these particles. 3)They fall as snow if surface temperatures are below or near freezing, or as raindrops at warmer temperatures. 4) Heat released as the droplets freeze boosts updrafts, which pull more moist air into the cloud.

Cloud seeding was pioneers in the United States in the 1940s. Efforts to control the weather began in the 1950s when Beijing was given access to “cloud seeding” data from the Soviet Union and today is kept alive at research facilities such as the Beijing-based Study Institute of Artificial Influence on the Weather.

Rain Making in China

China boasts the largest rainmaking program in the world ahead of Russian and Israel. According to the Weather Modification Research Center, China employs for than 50,000 people for the task and uses an arsenal that includes 6,781 artillery guns, 4,110 rocket-launchers. 30 modified planes, and some on trucks, are employed in the struggle to extract rain. Guns with shells that explode like fireworks are best for extracting rain from small, clouds while rockets, sometimes shot hundreds at a time, and planes are better for spreading chemicals over a wide area. The techniques are not used for bringing rain clouds to parched areas, only inducing clouds already in a given place to produce rain.

China is thought to have the world's largest rain-making operation. It has an annual budget of over $100 million and offices in 30 provinces. Between 1995 and 2003, China spent $266 million on rainmaking and $500 million on it between 2003 and 2008. Chinese scientists claim that cloud-seeding can increase precipitation in targeted areas by 10-15 percent. They claim Chinese rainmakers have increased rainfall by 210 billion cubic meters---enough to meet the annual needs of 400 million of China’s 1.3 billion people between 1995 and 2004. The current five year plan calls for an increase of man-made rain of 50 billion cubic meters a year---nearly enough to fill the Yellow River.

Rain Making Technology

The shells usually contain particles of silver dioxide, dry ice, or microscopic hygroscopic (water-absorbing) particles such as calcium chloride salts or liquid nitrogen. The idea is to get the cloud to adhere to the particles, causing water particles in clouds to swell into drops big enough to fall as rain.

Particles of silver dioxide resemble ice crystals. Supercooled water droplets in the clouds---too light to fall as rain---freeze on these “nuclei” causing each ice crystal to grow until it is heavy enough to fall as rain.

To prevent rain to a target area clouds are seeded so they dump their rain before they reach the targeted area or are seeded with many small seeds that spread over a wide area and disperse the water droplets making them unlikely to form nuclei large enough to fall as a raindrops.

Critics claim there is no proof the technology works and the chemicals can be harmful to the environment. The Chinese have done surprisingly little testing of the methods and few studies are available. According to a report on weather modification presented to the U.S. Congress rainmaking has been marked by “failure to provide scientifically demonstratable successes.”When clouds are seeded and rain falls, rainmakers claim success but who is to say the rain wouldn’t have fallen without seeding. There is no way to tell for sure.”

It is clearly an inexact science. One scientist told the Times of London, “You have to choose the right recipe of chemicals for the right kind of cloud. Otherwise it can do the opposite of what you want. And afterwards, how do you tell between man-made rain and natural rain?”

Rain Making in Certain Areas in China

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Plane used for cloud seeding
Among the successes of the Study Institute of Artificial Influence on the Weather was the creation of a rain storm that doused a massive forest fire in Heilongjiang in 1987 and then dispersed before a National Day Parade and Panda Festival.

In eastern Qinghai province, where crops have failed due to lack of rain, rockets filled with liquid nitrogen are fired into clouds. Liquid nitrogen spray causes ice droplets to form and drop as rain. The rainmakers monitor computers that measure air flows and cloud densities to decide when to fire. Scientist claim the efforts have produced 260 million cubic meters of rain and increased the flow of the Yellow River in Qinghai by 1.2 percent.

Twenty-three of China’s 43 provinces have weather modification bureaus. In some places different provinces and city’s fight over the same clouds. The biggest disputes occur when areas at the front of the prevailing wind seed clouds and get rain that might fall in another place further down wind. The effectiveness of the rain-inducing campaigns is a matter of debate. At best rainmaking operations produce only a 10 percent to 20 percent increase in rainfall. Because of wind direction and other variables even when rain is produced it often doesn’t fall where people want it.

Rain-inducing technology can also be used to make snow. In January 2007, rockets were fired into clouds over Changchun in Jilin Province in an effort to ensure there was enough snow there for the Asian Winter Games.

In 2004 four cities in Henan Province accused each other of “cloud theft.”

In February 2009, 12 highways around Beijing were closed by heavy snow after a cloud seeding operation.

See Beijing Olympics 2008.

Scientists 'Cause' Beijing Snow with Cloud Seeding

Quentin Sommerville of the BBC wrote: “Chinese meteorologists say they brought about Beijing's earliest snowfall in a decade, after seeding rain clouds with silver iodide to ease a drought.The Weather Modification Office sprayed clouds with 186 doses of the chemical to bring rain for the wheat crop, the Beijing Evening News said. But the arrival of a cold front caused heavy snow to fall, disrupting road, rail and air travel. [Source: Quentin Sommerville, BBC, November 2, 2009]

Cloud seeding is often used in China in an attempt to bring on rain. Despite the use of the cloud seeding technique, many scientists remain sceptical of its effectivenessIn February, snow fell after the authorities seeded clouds over Beijing in an attempt to alleviate the dry conditions. However, many scientists - particularly in the UK - remain highly sceptical of the effectiveness of cloud seeding. Even if it is theoretically possible, one of the problems for proponents has been to demonstrate that a rainfall or snowfall was caused by the seeding or simply occurred spontaneously.

Rainmaking Industry in China

Jiangxi Gangsi is one of the nation's biggest makers of cloud-seeding shells. Since 2000, the company has played a key role in China's weather-modification program. Workers on the assembly lines there encase catalytic chemicals  usually silver iodide or liquid nitrogen  in shells, which are fired by cannon or dropped from aircraft, to create water droplets in clouds that will fall as rain. [Source: Jonathan Watts, The Guardian, June 1, 2011]

Government officials encouraged local governments to make continued use of weather-modifying techniques. "We attach great importance to artificial rainfall in the effort to ease the drought," China Meteorological Administration vice director, Chen Zhenlin told The Guardian.

The production of the shells may be hindered by government price controls. Each cloud-seeding shell costs about 1,000 yuan ($140)--- a figure that has been set since 2000---which means there is little financial incentive to boost production. "We proposed a price increase to our senior executives," said Gu. "They sent a team to investigate the cost-production capacity. But these things take time." [Source: Jonathan Watts, The Guardian, June 1, 2011]

Preventing Hail in China

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Artillery used in hail prevention
To reduce damage from hail storms former military gunners are hired to use 1950s-era artillery and anti-aircraft guns to shoot explosive shells into storm clouds. In some places teams of women are paid $20 a head a month to do this. After receiving orders by radio they shoot into fast moving clouds. One weather station manager told the Los Angeles Times, “Not every attack works, of course...But most of the time, we attack and there’s no hail. We don’t attack and there is hail.”

The women are under relatively little supervision. After two weeks training they are organized into groups of four or five and assigned to a dozen or so mountaintops. They live is small barracks for six months of the year, during the hail season from May to October, with short break for trips home. They work as a team, with a loader, targeter, shooter and commander. Twice a day they contact the local weather bureau on old two-way radios for word on storms and weather conditions. Attacks are only carried out with a direct order over the radio.

Image Sources: 1) Dartmouth College; 2, 3) All Posters com http://www.allposters.com/?lang=1 Seach Chinese Art ; 4) NASA; 5) UNCCD; 6, 9) Xinhua; 7) AFP; 8) BBC; 10) The Hindu; 11) Gary Braasch

Text Sources: New York Times, Washington Post, Los Angeles Times, Times of London, National Geographic, The New Yorker, Time, Newsweek, Reuters, AP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.

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© 2008 Jeffrey Hays

Last updated July 2013


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