Weather patterns

Wind, Clouds,
and Precipitation

DIFFERENCES IN AIR PRESSURE

UNEQUAL HEATING OF AIR

Responsible for
triggering the initial
movement of air.

CORIOLIS EFFECT

SHIFT IN WIND
DIRECTION
DUE TO
EARTH’S
ROTATION

As air moves from high to low pressure in the northern hemisphere, it is deflected to the
right by the Coriolis force. In the southern hemisphere, air moving from high to low
pressure is deflected to the left by the Coriolis force.

Flushing Toilets on the Equator
Myth or Real:

Toilets flushed in the northern hemisphere
apparently spin to the right, in the southern
hemisphere the water spins left -- this is
supposedly caused by the Coriolis effect. And
on the equator? It's a straight shot down.

http://www.phschool.com/atschool/phsciexp/a
ve_art/global_winds/index.html

The global wind belts are formed by two main factors:
the unequal heating of the earth by sunlight and the earth's spin.

The unequal heating
makes the tropical
regions warmer than
the polar regions.
As a result, there is
generally higher
pressure at the poles
and lower at the
equator.
Source: http://www.islandnet.com/~see/weather/whys/globalwinds.htm

The atmosphere tries to send the cold air toward the equator at
the surface and sends warm air northward toward the pole at
higher levels.

Click on the link to watch an animation:

Animation 1 Animation 2
http://www.mhhe.com/biosci/g http://www.geography.hunter.cuny.edu/~t
enbio/tlw3/eBridge/Chp29/ani bw/wc.notes/7.circ.atm/animations/Globa
mations/ch29/global_wind_circ lWind.html
ulation.swf

GLOBAL WINDS
UNEQUAL HEATING
EQUALS
GLOBAL PATTERN OF AIR
CIRCULATION

LOCAL WINDS
LAND BREEZE
SEA BREEZE
MONSOON

SEASONAL WINDS
MONSOONS

CARRIES WARM MOIST AIR

Philippines
Northeast Monsoon (cold
and wet)

Southwest Monsoon (dry)

DOLDRUMS

CALM
SURFACE
WINDS AT
EQUATOR (0
degrees
latitude)

TRADE WINDS
AIR MOVING
BACK TO THE
EQUATOR
FORMING A BELT
OF WARM,
STEADY WINDS

HORSE LATITUDES

30 degrees North
and South of
Equator
Warm air cools and
sink; clear skies;
winds are calm

PREVAILING WESTERLIES

40-60 degrees
Latitude (West to
East)

Strong
Winds

POLAR EASTERLIES

COLD BUT WEAK
WINDS EAST
TO WEST

JET STREAMS

“rivers of air"
ABOVE 12 KMS
180-350
Km/Hr (speed)

http://www.youtube.com/watch?v=ODImMpGFUa4&feature=related

http://video.about.com/weather/How-Do-Clouds-Form-.htm

MOISTURE
CONDENSES ON
SMALL PARTICLES
OF DUST/ SOLIDS IN
THE AIR

DEW POINT
TEMPERATURE AT WHICH AIR
CONDENSES

MOLECULES COLLIDE
AND REBOUND SPEED
DECREASES

WHY RISING AIR COOLS

CONDENSATION
WATER VAPOR
CHANGES
INTO LIQUID

CLOUD FORMATION

WATER VAPOR
CONDENSATION NUCLEI
LOW TEMPERATURE

Source: http://www.vivoscuola.it/US/RSIGPP3202/umidita/lezioni/form.htm

Why do clouds have flat bottoms?

Dew point

Cloud
droplets

Ice

Snow

When warm air rises, other cooler air rushes in to take its place. The air that
rushes in moves parallel to the ground. It is this moving air that we call
“wind”.

Wind is caused by the uneven heating of the earth’s surface. Air that moves
up and down is important in making winds. This is called a current.

Warm air near the surface of the Earth can hold more moisture than cool air
above the Earth’s surface.

Water from the Earth’s lakes, oceans, land surfaces, and plants evaporates
into this warmer air. Eventually, the warm moisture-filled air rises and
becomes cool. Now the air can no longer hold all the moisture it had
acquired when it was near the surface of the Earth. As a result, much of the
water vapor in the air condenses.

Water vapor that condenses and forms clouds can fall to the Earth as
rain, sleet, snow, or hail. Water that falls from the atmosphere to
the Earth is called precipitation.

Hurricanes/Typhoons/
Cyclones & Tornadoes

http://www.youtube.com/watch?v=zP4rgvu4xDE

A hurricane is a tropical storm that has winds of 119
kilometers per hour or higher.
A hurricane begins
over warm water as
a low-pressure
area, or tropical
disturbance.

If the tropical
disturbance grows
in size and strength,
it becomes a
tropical storm,
which may then
become a hurricane.
http://www.youtube.com/watch?v=5iN352idLks&feature=fvwrel How Hurricanes Form

http://www.youtube.com/watch?v=5iN352idLks&feature=fvwrel How
Hurricanes Form

Hurricanes/typhoons/cyclones-what’s
in a name?
LOCATION, LOCATION, LOCATION

http://spaceplace.nasa.gov/hurricanes/

hurricanes/typhoons and tornadoes spin
COUNTER-CLOCKWISE
in NORTH

H

H H

H

http://edition.cnn
.com/2011/US/04
/28/severe.weath
er/index.html?hpt
=T2

http://edition.cn
n.com/2011/US/
04/27/tornado.o
utbreak/index.ht
ml?hpt=T1

Experts: Severe
weather across
South could set
tornado record

http://news.yahoo.com/s/yblog_thelookout/2
0110428/ts_yblog_thelookout/watch-
tuscaloosas-terrifying-tornado
Yahoo video clips

Tornado Outbreak
of 2011

The jet stream is the main reason for all
the severe weather. The warm humid
air from the south is clashing with the
cool dry air coming down from Canada
and where the two meet is where we
find severe thunderstorms and
tornadoes.

Including yesterday's storm, there
have been a whopping 800 reports
of tornadoes in April, easily
surpassing April 2003's all-time
record of 543 twisters.

http://www.nytimes.com/interactive/20
11/04/28/us/map-of-the-tornadoes-
across-the-south.html

Tornadoes Song:
http://www.youtube.com/watch?v=iOw6ONcKk4g

http://www.youtube.com/watch?v=cvOut9VUqKY&feature=fvwrel

http://news.yahoo.com/s/yblog_thelookout/2
0110428/ts_yblog_thelookout/watch-
tuscaloosas-terrifying-tornado
Yahoo video clips

Tornadoes

A tornado is a rapidly whirling, funnel-shaped
cloud that reaches down from a storm cloud to
touch Earth’s surface.

Tornadoes develop in low,heavy cumulonimbus
clouds—the same clouds that bring
thunderstorms.

http://www.youtube.com/watch?v=3Qu9wR03GV http://www.youtube.com/watch?v=VQDkmziz
A&feature=related 1n8&feature=fvwrel

http://www.youtube.com/watch?v=NTjR91JC850

Weather patterns

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