Upload
others
View
0
Download
0
Embed Size (px)
Citation preview
ATMOSPHERIC PRESSURE,
WIND & CLOUDS
Mt. Washington Observatory
ATMOSPHERIC PRESSURE
Weight of the air above a given area
p = F/A
Measured in mb (millibars)
Average Atmospheric Pressure at 0m
(Sea Level) is 1013mb
Your book
PRESSURE
50 miles
(Barometer measures 1013mb)
As you go up in altitude, there’s less weight (less molecules) above
you…
…as a result, pressure decreases with height!
PRESSURE
500mbpressure
1013mb pressure
ATMOSPHERIC PRESSURE
Your book
ATMOSPHERIC
PRESSUREPRESSURE
VARIATIONS
OVER PVDBarometers
Buybarometers.com
CAUSES OF
PRESSURE VARIATIONS
Universal Gas Law
Pressure depends on:
Number of Moles, Volume,
Density, and Temperature of all the air above PVD
PV = nRT
SEA LEVEL PRESSURE
VARIATIONS - RECORDS
Lowest pressure ever recorded in the Atlantic Basin: 882 mbHurricane Wilma, October 2005
Highest pressure ever recorded in the world: 1086 mbMongolia, December 2001
Pressure Differences cause Air to move
PRESSURE GRADIENT FORCE
EARTH’S ROTATION
ROTATION OF THE EARTH
ROTATION OF THE EARTH
ROTATION OF THE EARTH
ROTATION OF THE EARTH
ROTATION OF THE EARTH
CORIOLIS EFFECT
CORIOLIS EFFECT
WIND
WIND
HOW IS THIS APPLIED?
http://ww2010.atmos.uiuc.edu/(Gh)/wx/surface.rxml
MODERATE
SOUTH WINDS
NORTH WINDS
WARM
COLD
VALIDATION
Coolwx.com
L
VALIDATION
H
Coolwx.com
VALIDATION
NCAR UCAR RAP Realtime weather (http://www.rap.ucar.edu/weather/satellite/)
LH
SUMMARY UP TO THIS POINT1) Differences in atmospheric pressure across the globe
lead to winds across the surface of the planet
2) The PRESSURE GRADIENT FORCE pushes air
from high to low pressure (WIND)
3) The BIGGER the difference between high and low pressure
the STRONGER the wind
3) As air moves away from high pressure and towards
low pressure, the CORIOLIS EFFECT deflects it to its right (NH)
4) The above leads to air circulating COUNTER-CLOCKWISE
around LOW PRESSURE
and CLOCKWISE around HIGH PRESSURE (NH)
5) South or North winds will result in higher or lower temps
WHAT ABOUT THE CLOUDS?
Remember that air converges towards low pressure
and air diverges away from high pressure and
FRICTION due to the surface of Earth “enhances” this
WHAT ABOUT THE CLOUDS?
So, as the air moves towards the low pressure
it has nowhere to go but UPWARDS
WHAT ABOUT THE CLOUDS?
So, as the air moves away from high pressure
it must be replaced by air from above that is
moving DOWNWARDS
TEST
A World of Weather (Lee Grenci PSU)
INTERESTING NOTE!