Air-Sea Interactions II


I. General Circulation Caused by Coriolis Effect

  • contrary to what you may think, intensity of the Coriolis effect increases as you move towards the poles (not towards the equator) -- why?
    • not interested in absolute velocity, but rate of change of velocity -- there is a difference of 200 km/hr in velocity from equator to 30° latitude; a difference of 600 km/hr from 30 to 60° latitude; a difference of 800 km/hr in velocity from 60° to the poles
      • because of these velocity changes and the increase in the Coriolis effect, air movements in the polar cells are more complex
        • get formation of jet streams that are swiftly moving west-to-east currents high in the atmosphere that are located over the boundaries between a Ferrel and polar cell (or polar front)

II. Seasonal Variations in the Winds

In a warm front, warm air rises above cold air, condensing as it does so to form clouds and possibly rain.
When a cold front approaches an area occupied by warm air, the warm air is forced up, causing that air to expand and cool; this cooling will lead to condensation of water vapor and rainstorms will result.
  • Tropical cyclones ( Typhoons and Hurricanes): are formed from scattered thunderstorms of a tropical cloud cluster above very warm water (>26°C); they arise close to the equator, but far enough away for the Coriolis effect to exert a greater velocity and create vigorous eddies
    • within the center or eye, winds are light; around the eye there is a wall-like updraft that creates lower pressure which then fuels the storm by bringing in more hot, damp air
    • usually move westward but paths are erratic
    • break up upon hitting land
  • storm surges: results from a combination of high tides and rising sea level during periods of bad weather -- also characterized by low pressure systems that cause a bulge in the sea surface beneath them; these bulges and high winds cause high volumes of water to crash onto the shore (hurricanes can add to the winds pushing the water and water height)
  • waterspouts: weak, tornado-like phenomena caused by a rapid updraft of air and the accompanying inflow of low-level air -- most of the water is not sucked up from the sea but is caused by water droplets that form as the moist, rising air cools rapidly; is short-lived

III. Motion in the Sea -- Currents