Transcript Wind and Air Pressure

Local and Global Winds
► AIM:
How is wind created?
Do Now:
► Recall
what creates areas of higher and
lower air pressure.
► **FACT**
 Higher pressure air (H) is cooler, more clear,
and drier than Lower pressure air (L) which is
warmer, cloudier, and more moist.
Vocabulary
► Air
pressure
► Local winds
► Global winds
► Prevailing westerlies
► Isobars
► Cyclones
► Anti-cyclones
► Wind
Chill factor
► Anemometer
► Wind Vane
1. What is wind?
► Wind
– the horizontal movement of air
► ***Wind
is created when the uneven
heating of Earth’s surfaces creates areas
of high and low pressure***.
► Air
likes to move from
Higher pressure (H) to Lower pressure (L)
2. How is wind named and
measured?
►
Named by the direction
and speed from which it
comes. Ex. Westerly wind
comes from the West
►
Anemometer – measures
wind speed using cups
connected to a
speedometer
►
Wind vane – points to
direction that wind comes
from
3. What are local winds?
a. Local winds blow over short distances.
b. Part of the weather report. weather.com
c. Examples: Land breezes, sea breezes
► Observe
an animation of land and sea breezes.
4. Sea and Land Breezes
► During
day, warmer air
rises over the sand,
cooler air sinks over
sea.
► Air moves from water
to land = sea breeze
L
H
► During
night, cooler air
sinks over the sand,
warmer air rises over
sea.
► Air moves from land to
sea = land breeze
H
L
Sea and Land breezes are local winds that
affect us near TOBAY or Jones Beach
5. Larger local breezes
► Monsoon
– sea or
land breezes covering
a large area that
change directions
with the seasons
(Southeast Asia)
Monsoons
► Winter:
A large land
breeze, sinking higher
pressure air over land
keeps moist air off
shore =Good weather
► Summer:
A large sea
breeze, rising, moist
air from over the
ocean blows onto land
= Bad weather, rain
6. Global Winds
► Global
winds blow over a
long distance from a
specific direction
► Created
by uneven
heating of equator and
poles
 H = poles, cool, sinking
 L = equator, warm, rising
► Weather
patterns are
affected by the prevailing
winds in an area.
Name the prevailing winds that
affect each area…ESRT pg 14
► Latitude
– distance
from Equator
► Horse latitudes –
areas where air
sinks, at 30°N and
30°S
► Doldrums – areas
with little wind (at
the Equator)
7. Global Convection Currents
► Poles
have higher
pressure (cold air)
► Equator
has lower
pressure (warmer air)
► Air
sinks from poles
 Equator creating
convection cells
Bands of H and L air are created
The convection currents create a
distribution system for earth’s heat
http://www.youtube.c
om/watch?v=QbvHglF
yZbg&playnext=1&list
=PL9014F9D9475764
97
8. Why do the winds curve?
a.
The Earth’s rotation
curves the global
winds.
►
Right in the Northern
hemisphere
Left in the Southern hemisphere
►
a.
This is called
Coriollis Effect.
►
Coriolis Force: an artifact of the
earth's rotation
Observe an animation of the Coriolis
effect over Earth's surface.
►
► Jet
9. Jet Streams
stream – bands of high speed winds
► 200
to 400 kilometers/hour
► Up near the Tropopause
► Can “stear” weather and pollution patterns
http://www.youtube.com/watc
h?v=CgMWwx7Cll4
http://www.youtube.co
m/watch?v=UFC6819LS
5w&feature=related
ESRT pg 14.
Question…
► Why
do you think there are bands of wet and
dry air at the equator, 30o, 60o and 90 o?
10. Wind Chill factor
► Wind
chill factor – increased cooling, increased
evaporation, make the temperature feel colder. The
stronger the wind, the colder you feel!
Summary: What affect do winds
have on weather?
Moves weather
b. Creates weather patterns (seasonal changes)
c. Increases evaporation (dry things out)
d. Creates a wind chill (colder temperatures)
a.
http://www.youtube.com/watch?v=kPueXIHGQrg&feature=related
http://www.youtube.com/watch?v=fYfrWLhZy1A&feature=related
Pressure, Wind and Weather
Maps show us where the rising and
sinking air is…..
High vs. Low Air
High: Anticyclone
Clockwise, outward
More dense
Air sinks
Good weather
Dry air
►
Lows : Cyclones
Counter clockwise, inward
Less Dense
Rising air
Moist air
Bad weather
Warm air rises, cool air sinks
Isobars
► Isobars
are lines on a
map that connect
areas of equal air
pressure.
► Same
rules apply….
 Connect equal values
 Calculate gradient
 Steep side where lines
are closest together
Air moves from H to L
Pressure gradients
► Pressure
Gradient - the change in air
pressure with distance.
► The
windiest areas have the steepest
gradients.
► Calculate
the gradient between
A – B and C – D on the following map
A
D
B
C
Wind barbs
► Tell
us direction and
speed.
The wind is
blowing from the
southeast at 1520 mph
Draw the isobars
Barometric pressure on station models
In the plotted station model the 3 digit number to the
upper right of the station circle is the barometric
pressure.
It will look like 196 for pressures 1000 millibars and
higher: and 992 for pressures below 1000.
So, 196 means 1019.6 mb and 992 means 999.2 mb.
Basically, add a 10 in front of anything starting with a 0
or 1, and a 9 for anything starting with a 9.
Convert each station and then draw the isobars.
1016, 1012, 1008 and 996, 1004, 1008
1016 mb
H
L
996 mb
1012 mb
1000 mb
1008 mb
1004 mb