in search of the source of wind · the weight of atmospheric air on earth gravitational force helps...

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In Search of the

Source of Wind


Role of

Wind in

the

Voyage


The Weight of Atmospheric Air on

Earth

Gravitational force helps Air to

remain on Earth

Variations in the Atmospheric

Pressure are the Cause of Wind

Atmospheric Pressure


Variations in Atmospheric Pressure

Instrument

Mercury Barometer


Atmospheric Pressure -

Influencing Factors

Altitude Humidity

Temperature


Altitude & Pressure

Altitu

de

Pre

ssu

re

H

L

Less Amount of Air


Ooty

Paithalmala

Brahmagiri

Munnar

Ponnmudi


Temperature & Pressure

Te

mp

eratu

re

Pre

ssu

re

L H

Air Expands

When Heated

The Tropical Region Experiences Low

Atmospheric Pressure than Colder

Region because of the Difference in

Temperature


Hu

mid

ity

Pre

ssu

re

Quantity of Water Present

in the Atmosphere is

Humidity

L

H


Activity 1 ( Answer the Following)

1. Which are the Influencing Factors of

Atmospheric Pressure?

2. Find out the Relation between

a) Pressure & Altitude

b) Pressure & Temperature

c) Pressure & Humidity


Altitu

de

Pre

ssu

re

Te

mp

eratu

re

Pre

ssu

re

Hu

mid

ity

Pre

ssu

re

Relation with

Pressure


If the

Atmospheric

Pressure of

an Area is

Higher

Lower

Than

Surroundings

High & Low Pressure


Imaginary Lines

Connecting Places

Having Equal

Atmospheric

Temperature

Isotherms


H

L

Imaginary Lines

Connecting Places

Having Equal

Atmospheric

Pressure

Isobars


Activity 2

1. Which are the Different Global Pressure

Belts?

2. Write Short note on Different Global

Pressure Belts


50

N&S Latitudes

Low Pressure

Sun’s Rays Fall

Vertically through

out Year

High Temperature

Feeble Winds

‘Doldrums’ Zone

with No Winds

Equatorial Low Pressure Belt


Sub Tropical High

Pressure Belt

300

N&S Latitudes

High Pressure

Hot air from

Equator Cools here

due to Rotation


Sub Polar Low

Pressure Belt

600

N&S Latitudes

Low Pressure

Cold air is thrown

up due to Rotation


Polar High

Pressure Belt

900

N&S Latitudes

High Pressure

Severe Cold

throughout the

Year


Pressure

Belt

Latitudinal

Extent

Pressure Features

Equatorial

Sub

Tropical

Sub Polar

Polar

Activity 3 ( Complete the Table)


Pre. Belt L. Extent Pressure Features

Equatorial 50

N&S Low High

Temperature

Sub

Tropical

300

N&S High Air Cools due

to Rotation

Sub Polar 600

N&S Low Cold air is

thrown up

Polar 900

N&S High Severe Cold

Global Pressure Belts


Variations

in the

Amount of

Solar

Energy

Rotation

of Earth

Basis for Formation of

Pressure Belts


The

Pressure

Belts Move

According

to the

Apparent

Movement

of the Sun


Characteristics

Names based on Direction

Ocean Winds More Moisture



1. List the Factors Influencing the Speed and

Direction of Wind?

2. Write Short Note on :

a) Pressure Gradient Force

b) Coriolis Force

c) Friction


Pressure Gradient

Force (Speed)

Coriolis Effect

(Direction)Friction

(Speed)



1. Mark the direction of Winds

2. In which of these situations will the speed

of the Wind be higher? Why?


Pressure Gradient Force

High Speed Wind

Isobars are shown

Closely

Less

Speed

Wind

Isobar

s are

not

shown

Closely


William Ferrel (1817 –

1891) American Meteorologist

(Meteorology is the interdisciplinary

scientific study of the atmosphere)


Freely moving

Bodies get

Deflected :

Right NH

Left SH

Earth’s Rotation

is the Reason

Increases as it

moves from

Equator Poles

Ferrel’s Law


Winds


The Wind Formed

between the Global

Pressure Belts are

Planetary Winds

1. Trade Winds

2. Westerlies

3. Polar

Easterlies


North East Winds N Hemisphere

South East Winds S Hemisphere

Same Direction & Velocity

Rainfall in Eastern Cost

No Rain in Western-->Desert

Helped Sea Travelers

Subtropical Equatorial

High pressure Low


Subtropical Subpolar

High pressure Low

Westerlies Direction from West

Stronger in S H due to Vast Oceans

N Hemisphere S W – N E

S Hemisphere N W – S E

Different Names ‘Roaring 40s’,

‘Furious 50s’, ‘Shrieking 60s’


Polar– Sub Polar

High pressure – Low

Colder & Stronger

Blow from East in both Hemisphere

due to Coriolis Force (Polar Easterlies)

Role in the Climate of N America,

Eastern European Countries & Russia


Planetary

Winds

Area they Blow Direction of Wind

FeaturesHigh Pressure Low

Pressure

Northern

Hemisphere

Southern

Hemisphere

Trade

Winds

Westerlies

Polar

Easterlies

Activity 6 ( Complete the Table)


Planetary

Winds

Area they Blow Direction of Wind

FeaturesHigh

Pressure

Low

Pressure

Northern

Hemisphere

Southern

Hemisphere

Trade

Winds

Sub

Tropical

Equato

rial

North

East

South

East

Same

Direction &

Velocity

Westerli

es

Sub

Tropical

Sub

Polar

South

West

North

West

Stronger in

S H due to

Vast

Oceans

Polar

Easterli

es

Polar Sub

Polar

North

East

South

East

Colder &

Stronger


Periodic Winds

o For a Short Period

o At Certain Places

o Examples are

Monsoon Winds

Land & Sea Breeze

Mountain & Valley Breeze


Monsoon Winds

Due to Seasonal Changes

Seasonal Reversal in a year

o S W Monsoon Winds

o N E Monsoon Winds

Formation of Monsoon Winds – Factors

The Apparent Movement of Sun

Coriolis Force

Differences in Heating

Hippalus


Monsoon Winds


Southwest Monsoon

Sun Northern H

Pressure Belts Shift to North

Summer NH - HTemperature

As SE Trade Wind cross

Equator, Deflected (Coriolis

Force) and Transform into

Southwest Monsoon

Northeast Monsoon

Winter HP on Asia & LP on

Indian Ocean

Northeast Trade Wind Strengthened

& they are Northeast Monsoon

Arctic

Circle

Tropic of

Cancer

Equator

Tropic of

Capricorn

Antarctic

Circle

N

S

Polar HP

Polar HP

Sub Polar LP

Sub Tropical HP

Sub Tropical HP

Sub Polar LP

Equatorial LP

June 21

Sep 23

Dec 22

Mar 21

NE Trade Wind

SE Trade Wind


o The Planetary Winds In North European

Region blow on the Opposite Direction

o Winds are not From the Oceans

o Temperature difference between Land &

Sea is less

N

S

Polar HP

Polar HP

Sub Polar LP

Sub Tropical HP

Sub Tropical HP

Sub Polar LP

Equatorial LP

June 21

Sep 23

Dec 22

Mar 21

NE Trade Wind

SE Trade Wind

Monsoon Doesn’t Occur in N Europe

Reached Kerala with the help of Monsoon Winds

On Return he went against its Direction & it Troubled him

Vasco da Gama


Activity 7 (Comparison)

1. Make a Comparison Between Southwest &

Northeast Monsoon Winds

2. Make a Comparison Between Sea Breeze &

Land Breeze

3. Make a Comparison Between Valley Breeze &

Mountain Breeze


Southwest

Monsoon

Northeast

Monsoon

Direction South West

From Indian Ocean

North East

To Indian Ocean

Temperature NH High

SH Low (Indian Ocean)

NH Low

SH High

Pressure NH Low

SH High

NH High

SH Low

Season NH Summer

SH Winter

NH Winter

SH Summer


L

H

L

H


Valley

Breeze

Mountain

Breeze

Day Time At Night

Air in the

Valley Heated

up & Blows

upslope the

Mountain

Air in the

Mountain Cools

& Blows

towards the

valley


Local Winds

Smaller Locality

Result of Local Pressure Difference

E.g. (India) Loo, Mango showers,

Kalbaisakhi

E.g. (World) Chinook, Harmattan &

Foehn


Activity 8

Prepare a Table Showing the Name, Region and

Specialties of Local Winds

Wind Region Specialties

Chinook

Foehn

Harmattan

Loo


Wind Region Specialties

ChinookEastern

Slopes of

Rockies

Mountains

Melting Snow

Reduce Severity of Cold

Wheat Cultivation in

Canadian lowlands

FoehnSouthern

Valley of Alps

Reduce Severity of Cold

Harmattan Sahara Desert

W Africa

Dry Wind

Humidity & Sultry

Conditions Improved

LooNorth Indian

Plains

Hot Wind

Rise in Temperature


Activity 9 ( Complete the Flow Chart)


Planetary

Winds

Local

Winds

Periodic

Winds

Trade Winds

Westerlies

Polar Easterlies

Monsoon Winds

Land & Sea Breeze

Mountain & Valley

Breeze

Loo Chinook

Foehn Harmattan


Without the Sun’s Energy there would have been Nothing


Additional Activities

1. Difference between Isotherms & Isobars

2. Name the different Global Pressure Belts

3. What is Inter Tropical Convergence Zone (ITCZ)?

4. Which are the different names Westerly Winds?

5. Explain Doldrum

6.

7.

8.

9.

10.



Michael Angelo M.A. MA (Phi.,His.)

HSA(Social Science)

St. Mary’s H.S. [email protected]

9746953695

mailto:[email protected]

in search of the source of wind · the weight of atmospheric air on earth gravitational force helps...

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