A Land of Contrasts
It's ironic that the wettest place
in the world manages to thirst for water each winter when no rain falls
at all for months at a time. The type of weather phenomenon that brings
so much rain to this part of the world is called the monsoons.
Monsoons are seasonal winds that blow from one direction for approximately
six months, bringing torrential rains, and then blow from the opposite
direction for the remaining six months, during which little rain falls.
During the wet season moist air is cooled as it blows over rising land,
letting abundant rain fall on the windward side of mountain ranges.
But because of widespread destruction of conifer forests that protected
the soil, the ground does not absorb the rain that falls so heavily
during the monsoon season. The city of Cherrapunji is 1290 meters above
sea level and much of the torrential rains run off the mountains into
the valley below. The irrigation system for the town of Cherrapunji
is insufficient to provide adequate amounts of clean, potable water
from below during the dry season. People who live there frequently have
to travel on foot for several kilometers to bathe and get drinking water.
What Causes so much Rainfall?
The oceans are the chief source of
rain, but lakes and rivers also contribute to it. The sun's heat evaporates
the water. It remains in the atmosphere as an invisible vapor until
it condenses, first into clouds and then into raindrops. Condensation
happens when the air is cooled. For raindrops to form there must be
particulate matter in the air, such as dust or salt, at temperatures
above freezing. These particles are called condensation
nuclei. When the nuclei are cooled to temperatures below
the freezing point, water condenses around them in layers. The particles
become so heavy they resist updrafts and fall through the clouds as
rain.
In Cherrapunji it rains so much for two reasons:
Elevation: because of the elevation of Cherrapunji,
air that blows over the plains below is cooled as it rises to the
higher elevation. This cooling of the air causes the moisture trapped
in the air to condense, forming clouds, which then release rain.
Monsoons: the prevailing winds in that part
of the world are very heavily laden with moisture. The constant supply
of moist air for six months straight results in almost continual rainfall.
| Here's a place that holds a close second to
Cherrapunji: Mount
Waialeale, Kauai |
This place holds the unofficial
world record, because the record is an estimate
(523.6 in/13.3m): Lloro,
Colombia |
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| Coldest Place | Driest
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