1. "barometric pressure"
   • millibars = 1/1000 bar (1 bar = 1000 millibars)
     • millibars vs. height
   • sea level = 1013mb or 29.92 in.
   • "sea level pressure"
2. mercury vs. aneroid (and another example)
3. isobar

A. Constant Height Chart

B. Constant Pressure Chart

1. related to temps
2. ridges and troughs
   • current map

1. 1st law of motion: rest vs. motion
2. 2nd law of motion: force = mass x acceleration (F = ma)
   • equal & opposite ... PLUS ... force causes acceleration
   • demo

A. Pressure Differences = Pressure Gradient

1. caused by differences in temperature / density
2. air moves from high pressure to low pressure
   
3. greater diff. in pressure = stronger gradient
4. isobars: close together = strong gradient
   • isobars vs. wind speeds

1. due to rotation of the earth
2. deflection to right in northern hemisphere: *movie
   * animation from the University of Illinois WW2010 Project
   • imparts spin to air
3. faster wind speed = greater deflection
4. closer to pole = greater deflection
5. *geostrophic wind (straight isobars)
   * animation from the University of Illinois WW2010 Project
6. centripetal force (video demo)
7. gradient wind (curved isobars)
   • constant chg in direction = constant acceleration
   • curvature = magnitude of centripetal force

C. Friction

1. reduces wind speed which reduces Coriolis
2. causes "pinwheel", or spiral, rotation
   ( multiple storms example )
   • cyclonic (north = counterclockwise)
   • anticyclonic (north = clockwise)
3. wind direction varies with height   (today at TUS)

PRESSURE/WIND CHAPTERS ----->

Pressure

Local Wind

Global Wind