Earth Science, Tarbuck Chap 18 Flashcards
air pressure at sea level
1 kilogram per square centimeter, or 14.7 pounds per square inch. Also known as 1 atmosphere
Low pressure often correlates with what type of weather
Rainy/Stormy
how does air flow
Air flows from areas of higher
pressure to areas of lower pressure
3 factors that control wind
pressure gradient force, coriolis effect, and friction
What is pressure gradient force
amount of pressure change occurring over a given distance
How does spacing of isobars tell us the pressure gradient force and wind
Closely spaced isobars indicate a steep pressure gradient and strong winds; widely spaced isobars indicate a weak pressure gradient
and light winds
Where is the coriolis effect the strongest
Strongest at the poles, gets weaker until its non-existent at the equator
What are geostrophic winds
Wind blowing parallel to the isobar due to the coriolis effect balancing with the pressure gradient force. Only happens in high elevations, where wind is not affected by Earth’s friction
Coriolis effect is proportional to wind speed, what does that mean
the faster the wind, the more deflected it will be
At what angle is the coriolis effect applied
right angles
How does friction with Earths surface change wind
Friction slows wind speed, which leads to less deflection by the coriolis effect. Note this only applies to wind above the surface by a couple kilometers
What are cyclones
Areas of low pressure
What are anticyclones
Areas of High pressure
What direction are Cyclones blowing
In the north hemisphere, winds blow inward and counterclockwise, In the south, winds blow inward and clockwise
What direction are anticyclones blowing
In the north hemisphere, winds blow outward and clockwise, In the south, winds blow outward and counterclockwise
What usually causes cyclones to form
Divergence aloft
Why are low pressure systems a signal for rainy weather
Air converges and lifts, causing clouds to form.
Why are high pressure systems a signal for fair weather
Air diverges and clouds do not form.
Why is the air at the equator low pressure
Air at the equator is hotter which means its less dense and it rises more easily
What is the Subtropical High
When Air diverging from the equator reaches around 30 degree latitude North or South, it sinks back towards the surface, creating hot arid conditions due to adiabatic heating.
Diverging air at the subtropical high causes air to go where
Some of the air goes towards the equator, producing the trade winds, while the rest travels pole ward creating the westerlies
What is the polar front
As the warm westerlies encounter the cold polar easterlies, a stormy polar front is created
What is the polar high
At the poles, it is a high pressure system. This is due to air being colder and air traveling in from the mid latitudes.
What are polar easterlies
Polar high causes air to diverge toward the mid-latitudes
