SLIDE 1 ATMOSPHERIC PRESSURE, WIND & CLOUDS
- Mt. Washington Observatory
SLIDE 2 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
SLIDE 3
PRESSURE
50 miles (Barometer measures 1013mb)
SLIDE 4 As you go up in altitude, there’s less weight (less molecules) above
you…
…as a result, pressure decreases with height!
PRESSURE
500mb pressure 1013mb pressure
SLIDE 5 ATMOSPHERIC PRESSURE
Your book
SLIDE 6 ATMOSPHERIC PRESSUREPRESSURE VARIATIONS OVER PVD
Barometers
Buybarometers.com
SLIDE 7 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
SLIDE 8
SEA LEVEL PRESSURE VARIATIONS - RECORDS
Lowest pressure ever recorded in the Atlantic Basin: 882 mb Hurricane Wilma, October 2005 Highest pressure ever recorded in the world: 1086 mb Mongolia, December 2001
SLIDE 9
Pressure Differences cause Air to move
SLIDE 10
PRESSURE GRADIENT FORCE
SLIDE 11
EARTH’S ROTATION
SLIDE 12
ROTATION OF THE EARTH
SLIDE 13
ROTATION OF THE EARTH
SLIDE 14
ROTATION OF THE EARTH
SLIDE 15
ROTATION OF THE EARTH
SLIDE 16
ROTATION OF THE EARTH
SLIDE 17
CORIOLIS EFFECT
SLIDE 18
CORIOLIS EFFECT
SLIDE 19
WIND
SLIDE 20
WIND
SLIDE 21 HOW IS THIS APPLIED?
http://ww2010.atmos.uiuc.edu/(Gh)/wx/surface.rxml
MODERATE SOUTH WINDS NORTH WINDS
WARM COLD
SLIDE 22 VALIDATION
Coolwx.com
SLIDE 23 L
VALIDATION
H
Coolwx.com
SLIDE 24 VALIDATION
NCAR UCAR RAP Realtime weather (http://www.rap.ucar.edu/weather/satellite/)
L H
SLIDE 25
SUMMARY UP TO THIS POINT
1) 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
SLIDE 26
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
SLIDE 27
WHAT ABOUT THE CLOUDS?
So, as the air moves towards the low pressure it has nowhere to go but UPWARDS
SLIDE 28
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
SLIDE 29 TEST
A World of Weather (Lee Grenci PSU)
SLIDE 30
INTERESTING NOTE!
