Download investigating monsoons

InspirEd Explorer
June 61 1999
INVESTIGATING MONSOONS
NEW DELHI, INDIA - Frequently the
monsoon season brings devastating
floods to countries in southern and
Southeast Asia. While the rains are vital
to the region's food supply, they can
also bring death. This week saw the end
of a six-week study of the monsoons.
Researchers found important clues to the
summer monsoons that may help meteorologists predict the timing of the rains.
Researcher PeterW ebster stated, "Roughly 65 percent of the world's population
lives in monsoon regions. This is the fastest growing region on the planet. By the
year 2025, it is anticipated this number will grow to 75 percent." The ability to
predict the onset of the summer rains could save thousands or even millions of lives.
Monsoons are large air masses in the tropics that move onto land from the sea
during the summer and from the land back to the sea in winter. The word "monsoon"
comes from "mawsin," the Arabic word for "season," since the winds change
direction seasonally. Unlike temperate regions, the tropics have only two seasons,
wet and dry. During the summer rainy season as much as 30 inches of precipitation a
day can fall! The winter pattern brings dry conditions that can cause droughts.
Minor changes in the pattern can greatly affect the people of the region .. Too much
or too little rain can spell disaster for subsistence farming and can mean the difference
between eating or not for many families of southern Asia. Rainfall from June to
September provides countries such as India and Bangladesh with almost 90 percent of
their water supply, so too little rain leaves the region with serious drought conditions.
Too much rain, on the other hand, brings floods and landslides that can wipe out
entire villages. Last year flooding along the Chiang Jiang River killed more than
3,700 people and caused more than $30 billion in damage.
Scientists use satellite information to study the wind patterns that occur over the
Indian Ocean and the South China Sea. During the winter months cold, dry air flows
from the Arctic across Asia. Then sometime during the spring the flow of air reverses
and warm, wet, air from the south brings the rains. Researchers believe that the flow
of air is determined by air pressure, since air moves from where pressure is high to
where it is low. If scientists could discover why the flow reverses, they could better
predict when rains and floods may occur. This study did find a possible link between
the beginning of the summer monsoons and cyclones, whirling windstorms occurring
in the ocean, but more research is needed.
Summer monsoon rains are essential to crops in southern Asia and bring water to a
region that depends on them. But the same rains can also be deadly. Floods and
landslides kill thousands of people each year, and changes in the timing of the rains
can bring drought and famine. Until scientists can better understand and predict the
weather pattern, the monsoons will continue to be a blessing and a curse to the region.
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