Weather and Climate Ch4

  1. pressure
    The gas molecules pulled to the Earth by gravity exert a force on all surfaces they are in contact, and the amount of that force exerted per unit of surface area is pressure.
  2. pascal (Pa)
    standard unit of pressure (but in Us it is millibar[mb])
  3. kilopascal (kPa)
    Canadian standard unit of pressure
  4. Dalton's Law
    The total pressure exerted is equal to the sum of the partial pressures.
  5. surface pressure
    air pressure as it exists at the surface
  6. sea level pressure
    the pressure that would exist if the observation were at sea level.
  7. speed
    the distance traveled per unit of time.
  8. velocity
    much like speed but also incorporates direction (speed and motion of an object or substance). So, distance traveled per unit of time + direction.
  9. acceleration
    the change in velocity (not speed) with respect to time.
  10. gravity (g)
    an acceleration that is a near constant around the globe (9.8 m/sec/sec)
  11. force (F)
    the net force acting on an object.
  12. equation of state (ideal gas law)
    if the air density increases while temperature is held constant, the pressure will increase.
  13. mercury berometer
    standard instrument for measurement of pressure
  14. barametric pressure
    inconsistent because pressure is not measured by length as with a mercury berometer, which is used to measure barametric pressure to find the height of the column of mercury.
  15. aneroid berometer
    air inside is compressed by the outside air pressure. canbe quite cheap and accurate.
  16. barographs
    aneroid barometers that plot continuous pressure
  17. isobar
    isobars are lines on weather maps plotted to show continous pressure patterns
  18. pressure gradient
    rate of change n pressure
  19. pressure gradient force
    the pressure gradient gives rise to a force that sets air in motion (wind) called pressure gradient force.
  20. hydrostatic equilibrium
    the vertical gradient pressure force and gravity are of equal pressure (hydrostatic equilibrium) therefore, we can breathe easily without air being sucked to the surface.
  21. hydrostatic equation
    (formula of hydrostatic equilibrium) The rate at which pressure decreases with height equals the product of the air density and the acceleration of gravity.
  22. Coriolis force
    (one of 2 factors that effect the movement of air) The phenomenom in which the rotation of the Earth has an effect on anything that moves in a certain direction, including wind, which the rotation of the Earth deflects (turns).
  23. friction
    (one of 2 factors that effect the movement of air) air in contact with surface experiences frictional drag, which decreases wind speed. The air above this slowed air is then slowed by the slowed air below.
  24. planetary boundary layer (boundary layer)
    lowest 1.5 km (1 mile) of the atmosphere
  25. free atmosphere
    atmosphere above the lowest 1.5 km (1 mile) of atmosphere
  26. geostrophic flow (geostrophic wind)
    when the pressure gradient force is equal to the Coriolis force, the air flow becomes unaccelerated, with unchanging speed and direction.
  27. equation of motion
    states that the acceleration experienced by a mass of air is the sum of the accelerations due to the three forces of Coriolis force, pressure gradient, and frictional acceleration.
  28. gradient flow (gradient wind)
    the continual mismatch between the Coriolis forces and pressure gradient resulting in winds changing speed and direction.
  29. supergeostrophic flow
    when the Coriolis force exceeds the pressure gradient force air is forced to turn clockwise.
  30. subgeostrophic flow
    (opposite of supergeostrophic flow) Coriolis force is weaker than the pressure gradient force, causing the air to turn counter-clockwise.
  31. anticyclones
    Enclosed areas of high pressure marked by roughly circular isobars or height contours where air spirals clockwise.
  32. cyclones
    Closed low-pressure systems where air spirals counter-clockwise.
  33. troughs
    low pressure pressure systems
  34. ridges
    high pressure systems
  35. azimuth
    a wind's degree of angle from due north moving clockwise. used to express wind direction.
  36. wind vane
    observes wind direction
  37. anemometers
    measures wind speed
  38. aerovane
    indicates wind direction and speed
  39. rawinsondes
    radiosondes whose movement is tracked by radar
Card Set
Weather and Climate Ch4
Weather and Climate Ch5