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
What are monsoons
large-scale seasonal wind systems characterized by their reversal in direction, usually accompanied by significant changes in rainfall patterns.
What is required for a monsoon to occur
Landmass is near large body of water, areas are in subtropical to tropical locations,
What is a summer monsoon
During the summer, the land heats up faster than the surrounding ocean.warm land causes air to rise, creating a low-pressure area over the continent.Cooler, moist air from the ocean is drawn inland, where it rises, cools, and condenses, leading to heavy rainfall.
What causes sea breezes
During the daytime in summer, especially around noon, the land heats up faster than the sea, causing the cool air from the sea(High pressure) to move towards the warm air on the land(Low pressure)
What are Land breezes
During the nightime of summer, the sea is warmer than the land, which cools faster, causing the cool air from the land(High pressure) to move towards the warm air on the sea(Low pressure )
What is a Valley Breeze
During the day, the sun heats up the slopes of mountains faster than the valley floor. Cooler air from the valley moves upward along the slopes.
What is the mountain breeze
During the night, rapid radiation cooling along the mountain slopes produces a layer
of cooler air next to the ground. Because cool air is
denser than warm air, it drains downslope into the valley.
Valley breezes often occur in what season
Summer
Mountain breezes often occur in what season
Winter.
What are chinooks
Warm, dry winds moves down the eastern
slopes of the Rocky mountains
What is a prevailing wind
When the wind consistently blows more often
from one direction than from any other,
What is el nino
an irregularly occurring and complex series of climatic changes affecting the equatorial Pacific region and beyond every few years, characterized by the appearance of unusually warm, nutrient-poor water off northern Peru and Ecuador, typically in late December.
What is La nina
essentially the opposite of El Niño and refers to colderthan-normal sea-surface temperatures in the
central and eastern Pacific. Happens immediatly after El nino
El nino has what impact on Hurricanes
Reduces the amount of atlantic hurricanes
La nina has what effect on weather
Leads to wetter weather
Effect of La nina on hurricanes
More Atlantic hurricanes
What is Southern Oscillation
seesaw pattern of atmospheric High and Low pressure
between the eastern and western Pacific
