Atmosphere - Horizontal Circulation Flashcards
General Atmospheric Circulation
Refers to any atmospheric flow of the Earth, and regional movements of air around area of high and low pressure.
Horse Latitudes
About 30 degrees north/south of the equator
Which way do NH winds blow depending on the pressure of the system?
Clockwise in HPS and counter-clockwise in LPS
Which way do SH winds blow depending on the pressure of the system?
CCW in SPS and CW in LPS
Why is atmospheric circulation important for ecosystems?
Solar radiation is unevenly distributed, thus important in temperature regulation.
What would a horziontal atmospheric field of pressure with no variation mean for terrestial/ocean lands?
Sea heats and cools slowly over the day whilst terrestial lands drastically fluctuate, being hot at day and equally cold at night.
What happens when land temperature increases?
Air rises, forcing air above to rise, with pressure at the surface due to overlying air.
Due to physics of sea/land surface atmosphere, what happens at shore transition zones?
Forcing pressure towards sea during summer due to pressure gradients, with circulation due to the now decrease pressure on land.
How does surface pressure relate to land/sea?
Low pressure surfaces on land, with high pressure surfaces above oceans.
Hadley Cell
An atmoshperic convection cell where air rises at the equator, sinking in medium latitudes(30 degrees north and south)
Why does the equator spin faster than the poles?
It is wider, travelling 1,000 mph
What would a northward bound air pocket at constant speed from the equator do?
Diverge eastwards
Why do air masses move eastwards in the NH?
Its equatorial velocity is larger than the velocity of the solid earth below.
What did hadley propose to explain easterly winds?
Momentum transfer from air to ground at the equator reduces wind speed, flowing easterly due to being unable to keep up with increasing speed.
Angular Momentum
The quantity rotation of a body, the product of its inertia and angular velocity.
What does Hadleys Model neglect?
The conservation of nangular momentum nor changing velocities.
Inertia
A property of matter, where it continues in its existing state of rest in a straight line, unless changed by a force.
Coriolis Force
A force relative to the surface of the Earth, causing deflection of moving objects to the ing in the NH and left in the SH.
What does Newton say about velocity change?
There is accompanied acceleration, implying a force.
What force causes angular momentum of atmosphere?
Coriolis force
What is an important note on the Coriolis forc
The object itself is not moving, only the surface below it
Why else does an air mass deviate from its path?
The tangenital velocity of a location of Earth, relates and is dependent on latitude.
What is an example of coriolis force in effect?
If you fired something from the equator northwards, it would land east of its target, east rotation being faster than the eqwuator.
Centrifugal Force
A force arising from a bodys inertia, causing an object moving in a circular path to move out and away from the center of its path.
Explain centrifugal force
If a particle at constant speed is moving at the circumfernce of a circel, a force(centripetal force) is required to kepe that constant velocity TOWARDS centre of a circle, with an opposing force keeping it from the centre, the centrifugal.
What is an example of centripetal force?
A string from the circle with tension force.
What causes westerlies?
Hadley circulatioin flows to about 30 degrees, terminating, air sinks to surface, returns to tropic at ground level, coriolis directs it westward
Geostrophic Current
This is a current where the pressure gradient force is balance by the coriolis effect.
Pressure Gradient Forces
Forces when there is a difference in pressure across surface.
What does atmosphere vertical structure reflect?
Vertical pressure gradients pushing upwards and gravitational forces pulling downards
What is an example of Geostrophic current?
A NH air mass in a west-east pressure gradient subjects to eastern movement by coriolis until a point air masses coriolis force exactly cancels out pressure gradient force.
How does geostrophic currents reflect in low pressure systems?
Stationary air mass moving towards a direction, moving right in NH in CCW due to coriolis force, thus geostrophic balance.
What do frictional forces do?
Transfers linear motion to the surface of contact, changing the linearity due to an imposed force.
What causes change of lienarity when wind recieves friction?
Friction opposes direction of the air
