Transcript Chapter 27 - Edison High School

Chapter 27
Waiting for the Rains: The Effects of
Monsoons in South Asia
27.1 Introduction
Monsoons – strong and violent seasonal winds
blow in from the ocean each summer, carrying
with them clouds heavy with moisture
• Almost all of the rain in South Asia each year
comes from these rains
27.2 The Geographic Setting
Indian Subcontinent – is the giant triangle
peninsula located in the Indian Ocean
• 1 out of every 5 people on earth lives in South
Asia
• Most of these people are farmers who both
look forward to and fear the rain
27.2 Continued
How are Monsoons Created?
• Atmospheric Pressure Change
1. There is high pressure – cool air from upper
atmosphere presses down towards the earths surface
(usually means sunny and no rain)
2. There is low pressure - warm surface air moves into the
upper atmosphere (if air is moist it forms clouds that
bring rain)
• Air from high-pressure areas will naturally flow into
low-pressure areas which creates wind
• The Indian Ocean is much cooler than the lands surface
which helps generate Monsoons
27.2 Continued
Mountains will effect were the storms will drop
their moisture
• Upwind slopes (against wind) will receive large
amount of rain
• Downwind slopes (with wind) receive less rain
• Geographers call this the Orographic Effect
27.3 The Wet Months in Dhaka,
Bangladesh
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10 million people live in Dhaka
In 1996 – about 3 million died from flooding
July is a tough month
Most of Bangladesh lies on the river delta
80 inches of rain a year (1 of the wettest)
From November to April it gets very dry
27.3 Continued
Life depends on the rains
• 3 out of every 5 people farm
• Too much rain causes everything to stop (can’t
plant or harvest, vehicles can’t move, flooding
happens)
• Polluted drinking water is a major problem
27.4 The Dry Months of Jodhpur,
India
A city on the edge of a desert
• Jodhpur sits on the Eastern edge of the Thar Desert in
Northern India
• Semiarid most of the year
• Receives 14 inches of rain between June & September
from the monsoons
• 80% of people here farm
• If rain is late or not enough farmers will not have a crop
1. This leads to disease and starvation
2. Some try to survive on Samas (wild grass)
• To conserve water farmers have started to use drip
irrigation (water dripped directly into crop roots)
27.5 Waiting for the Rains in
Calcutta, India
Wet Summers & Dry Winters
• About 15 million live here (1/3 live in slums)
• Monsoons from June to September can drop 50
inches of rain and bring 100 degree heat
• The city slows, children wade through water to
get to school
• Old canals clog with garbage, standing water
brings mosquitoes, they can spread disease
• The city is working on repairing sewer systems
and helping with flooding issues
27.6 Living in the Rain Shadow:
Pune, India
Located on the Deccan Plateau in Western India,
totals 29 inches of rain a year while Mumbai
(115 miles away) gets 70 inches
A Year-Round Dry Climate
• Western Ghats mountains lie between
• Pune sits on the downwind side of the
mountains
• Live on less water, grow sugar beats and not
sugar cane (Takes less water)
27.6 Continued
• They have practiced Cloud Seeding (spreading
chemical into clouds to bring rain)
• These people live in the Rain Shadow