Atmospheric and ocean circulations Flashcards
one of the most important outputs of the Earth-atmosphere energy system
global circulation of winds and ocean currents
true or false
our atmosphere is shared by all humanity
true
air pressure
the weight of the atmosphere described as force per area
air pressure is due to the
weight of the air above us
air pressure is key to understand
wind
air pressure makes _____
gradients
_____ and _____ decrease with altitude in the atmosphere
density and pressure
what affects density
water vapour in the air
moist air is ______
lighter
why is moist air lighter
the molecular weight of water is less than that of the molecules making up dry air
warm, humid air is associated with
low pressure
cold, dry air is associated with
high pressure
a ______ is used to measure atmospheric pressure
barometer
how does a barometer measure atmospheric pressure
using liquid mercury because mercury reacts to changes in pressure
an ______ barometer is used to measure pressure without liquid
aneroid
how is atmospheric pressure measured today
by electronic sensors that provide continuous measurements over time
how to compare pressure conditions from place to place
pressure measurements are adjusted and compared to a standard of normal-sea level pressure
standard atmosphere and pressure at sea level
temp = 15 degrees Celcius
pressure = 101.325 kPa
density = 1.23 kg/m3
what scales are used to measure pressure
- millibars
- inches of mercury
what is the normal range for air pressure
980 to 1050 mb
wind
the generally horizontal motion of air across earth’s surface
anemometer
measures wind speed
wind vane
determines wind direction
winds are named for the
direction from which they originate
wind is Lethbridge is often moving
westerly (west to east)
four forces that determine both the speed and direction of wind
- gravitational force
- pressure gradient force (PGF)
- Coriolis effect
- friction force
PGF
drives air from areas of higher barometric pressure to areas of lower
gradient
rate of change in some property over distance
can there be wind without a pressure gradient force
NO
does air motion have to be horizontal to create pressure gradients
NO, it can also be vertical
at higher pressure there are ____ winds
lighter
low pressure there is _____ winds
strong
why is the flow of wind a vector
it has speed and direction
thermal circulation system
occur with horizontal PG created by contrasting thermal environments
Aloft
what is above us
at a higher pressure the air is _____ (cold or warm)
cold
at a low pressure the air is _____ (cold or warm)
warm
what is used to balance the imbalance in pressure
wind to move matter