Exam 2 Flashcards
(121 cards)
Coriolis Force
Affects wind direction The apparent deflection of wind and objects relative to the Earth’s surface caused by the rotation of Earth. Deflection right in Northern hemi, left in southern hemi, direction shift increases with latitude.
Three-Cell Model
Geostrophic Flow
Occurs when pressure gradient force = Coriolis force. Air flows parallel to lines of equal pressure. Rare in nature
Gradient flow results from:
a nonuniform pressure gradient
Surface winds are NOT parallel to isobars because:
of friction, reduces wind speed, and therefore reduces Coriolis force
Anticyclones
air diverges from high pressure areas at surface and is deflected by Coriolis force. Clockwise N, counter S. Effect: descending air that warms and creates clear skies.
Cyclones
Air converges toward low pressure center at surface and is deflected by Coriolis force. Counter N, Clockwise S. Effect: ascending air that cools to form clouds.
Unclosed pressure systems are…
elongated areas called troughs and ridges
Single Cell Model
General movement of atmosphere. Heating at equator causes air to expand upward and diverged towards the poles, eventually sinking to the surface and returning to the equator. Easterly surface winds.
Define easterly winds
From east to west
Define westerly winds
From west to east
Three Cell Model
Divide each hemisphere into three cells: Hadley cell, Ferrel cell, Polar cell. With different air circulation patterns. Describes climate patterns.
Hadley Cell
Intense heating at equator creates the equatorial low belt of pressure. Pressure and wind model considered close approx of real world.
ITCZ
Intertropical Convergence Zone, region around equator where trade winds of N and S hemispheres come together
Ferrel Cell
Circulates surface air between subtropical highs and subpolar lows (middle). Deflected by Coriolis, causing westerlies.
Polar cell
circulates surface air between polar highs and subpolar lows. Deflected by Coriolis, causing easterlies.
How accurate are Ferrel and Polar cells?
Does not capture real world well.
Semi-permanent pressure cells
Instead of cohesive pressure belts, there are semi-perm high and low belts that fluctuate seasonally.
Monsoons are caused by:
continental surface heating; seasonal thermal differences between land masses and large bodies of water.
Winter monsoons
Dry air flows southward from the Himalayas. Offshore flow.
Summer monsoons
Moist air is drawn northward from the equatorial oceans. Onshore flow.
Land cools or heats _______ than water
faster
Sea breezes are caused by:
heating and cooling differences between land and ocean
How do sea and land breezes travel?
Land breeze: during day, land is warmer so air expands and rises and moves towards sea.
Sea breeze: during night, water is warmer, so air moves back to land.