AIR PRESSURE
FORCES
AND WIND
Definition:
The difference in
atmospheric
pressure per unit
distance
PGF acts at right
angles to isobars
of equal pressure
H
L
102.2
99.8
101.4
100.6
600 km
Pressure Gradient Force = 2.4 kPa / 600 km
= 0.4 kPa / 100 km
Where are winds strongest ?
Oct 18, 2004 Solution: HUDSON BAY
Check the spacing of the isobars of equal surface pressure
Source: NASA
Surface roughness decreases wind speed
Reduces impact of Inertial Coriolis Force
Winds cross isobars, spiralling out of
ANTICYCLONES (H), and into CYCLONES (L)
H
L
weather.unisys.com
H
L
Air tends to be unstable in low pressure (tendency to rise)
Air tends to be stable in high pressure (tendency to fall)
1. Equatorial Low Pressure Trough
2. Subtropical High Pressure Cells
3. Subpolar Low Pressure Cells
4. Weak Polar High Pressure Cells
ICE CAP
TUNDRA
BOREAL
MIXED TEMPERATE
BROADLEAF
DESERT
SAVANNA
RAIN FOREST
SAVANNA
DESERT
MIXED TEMPERATE
TUNDRA
ICE CAP
How does this relate to the “jet stream”?
Geostrophic wind
(above strong influence of friction)
CHAPTER 10
ULTRASONIC SOUND
WAVES DETERMINE
WIND SPEED,
DIRECTION &
TEMPERATURE
Sonic
http://www.wrds.uwyo.edu/wrds/rmfres/fendrift.htm
Also SW Ontario
Cooling
At MALR
6°C/km
Cooling
At MALR
6°C/km
Warming
At DALR
10 °C/km
Warming
At DALR
10 °C/km
Cooling
At DALR
10 °C/km
X
VANCOUVER
8°C
X
LETHBRIDGE
12°C
More sensible heat
Santa
Ana
Winds
Entrained Particle
Exposed section
Buried Portion
Which circulation cell extends
from the equator to the subtropics?
A. Polar cell
B. Hadley cell
C. ITCZ
D. Ferrel cell
Which circulation cell extends
from the equator to the subtropics?
A. Polar cell
B. Hadley cell
C. ITCZ
D. Ferrel cell
Which circulation cell extends
from the subpolar lows to the poles?
A. Polar cell
B. Hadley cell
C. ITCZ
D. Ferrel cell
Which circulation cell extends
from the subpolar lows to the poles?
A. Polar cell
B. Hadley cell
C. ITCZ
D. Ferrel cell
Which circulation cell extends
from the subtropics to the subpolar lows?
A. Polar cell
B. Hadley cell
C. ITCZ
D. Ferrel cell
Which circulation cell extends
from the subtropics to the subpolar lows?
A. Polar cell
B. Hadley cell
C. ITCZ
D. Ferrel cell
Which global wind belt is between
the subtropical highs and the subpolar lows?
A. trade winds
B. westerlies
C. ITCZ
D. easterlies
Which global wind belt is between
the subtropical highs and the subpolar lows?
A. trade winds
B. westerlies
C. ITCZ
D. easterlies
Which global wind belt is between
the ITCZ and the subtropical highs?
A. trade winds
B. westerlies
C. ITCZ
D. easterlies
Which global wind belt is between
the ITCZ and the subtropical highs?
A. trade winds
B. westerlies
C. ITCZ
D. easterlies
What occupies the region labeled “A”?
A
A. cyclone
B. jet stream
C. tornado
D. semi permanent cell
What occupies the region labeled “A”?
A
A. cyclone
B. jet stream
C. tornado
D. semi permanent cell
What are the dashed lines?
A
A. isotherms
B. isobars
C. pressure heights
D. isohyets
What are the dashed lines?
A
A. isotherms
B. isobars
C. pressure heights
D. isohyets
What do the lines on this map show?
A. many isobars
B. a cold front
C. a middle latitude cyclone
D. Rossby waves
What do the lines on this map show?
A. many isobars
B. a cold front
C. a middle latitude cyclone
D. Rossby waves
Which season is depicted in the photo?
A. summer
B. winter
C. fall
D. spring
Which season is depicted in the photo?
A. summer
B. winter
C. fall
D. spring
Where will the Santa Ana winds likely occur?
A. New York
B. Florida
C. Texas
D. California
Where will the Santa Ana winds likely occur?
A. New York
B. Florida
C. Texas
D. California
Which type wind is depicted?
A. katabatic wind
B. land breeze
C. sea breeze
D. Santa Ana wind
Which type wind is depicted?
A. katabatic wind
B. land breeze
C. sea breeze
D. Santa Ana wind