Unit 6 Flashcards
What is the Pressure Gradient Force (PGF)?
It initiates wind movement by causing air to move from high to low pressure. The greater the pressure difference, the stronger the PGF and the faster the wind.
What is the Coriolis Force?
Due to Earth’s rotation, it deflects moving air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. It is strongest at the poles and weakest at the equator
What role does friction play in wind movement?
Friction acts near the surface to slow the wind down, reducing the Coriolis effect and allowing PGF to have more influence. It causes air to spiral into low-pressure systems and out of high-pressure systems.
How do balanced forces affect wind movement?
When PGF and Coriolis force are balanced, geostrophic wind occurs, flowing parallel to isobars.
What is the behavior of geostrophic wind in the Northern Hemisphere?
It flows clockwise around high pressure and counterclockwise around low pressure.
What is the Gradient Wind?
A geostrophic wind that accounts for curved isobars and includes centripetal force, keeping the wind moving in circular path
What happens when forces are not balanced near the surface?
Friction slows the wind, reducing the Coriolis force, allowing PGF to dominate, causing convergence into low-pressure areas (rising air and clouds/stormy weather) and divergence from high-pressure areas (sinking air and clear skies).
What is the Hadley Cell?
It is a circulation pattern from 0° to 30° latitude where warm air rises at the equator, moves poleward, cools, and sinks at 30°.
What is the One-Cell Model?
An early simplistic model where warm air rises at the equator and sinks at the poles, not accounting for Earth’s rotation
What is the Three-Cell Model?
It accounts for Earth’s rotation and Coriolis force, dividing circulation into Hadley Cell (0°–30°), Ferrell Cell (30°–60°), and Polar Cell (60°–90°).
What is the Intertropical Convergence Zone (ITCZ)?
A region where warm, moist air rises at the equator, leading to heavy rainfall and tropical weather.
What is the Polar Front?
The boundary between cold polar air and warm mid-latitude air, associated with storm systems.
What are the six wind belts?
Three per hemisphere: Trade Winds (0°–30°) blowing from east, Westerlies (30°–60°) blowing from west, and Polar Easterlies (60°–90°) blowing from east
What climate effects are associated with surface convergence zones?
.
They lead to wet climates, such as those found in the ITCZ
What climate effects are associated with surface divergence zones?
They lead to dry climates, such as those found in subtropical highs.
Where are the Mid-Latitude Westerlies found?
They are found between 30° and 60° latitude, in a zone of mixing between warm and cold air.
What occurs in the Mid-Latitude Westerlies?
Major storm tracks occur in this region.
