Air Pressure

mercury barometer

barometer in which changes in air pressure are measured by changes in the height of the column above mercury in the dish.

(cold or warm) air is associated with low air pressure.

warm

HIGH pressure = _______ weather

"fair"

LOW pressure = ________ weather

"stormy"

atomic mass of Hydrogen atom

1 amu

atomic mass of nitrogen atom

14 amu

atomic mass of oxygen atom

16 amu

standard air pressure at sea level

29.92 in Hg OR 1,013 mb

What is the air pressure at the summit of Mt. McKinley?

525 mb

What is the elevation of Mt. McKinley?

6193 m

Air density changes with:

ALTITUDE, TEMPERATURE, HUMIDITY

humidity

Air pressure decreases as the humidity of air increases.

In which state is Mt. McKinley located?

Alaska

Humid Air

As less massive water vapor molecules are added to air, the humidity of this air will increase; As humidity of air increases, the density of air becomes less and air pressure becomes lower.

As air humidity INCREASES, air density DECREASES and air pressure

DECREASES

As air temperature INCREASES (gets warmer), air density

DECREASES

As air temperature INCREASES, air density DECREASES and air pressure

DECREASES

As altitude INCREASES, air density DECREASES and air pressure

DECREASES

As altitude above Earth's surface INCREASES, air density

DECREASES

As the density of air DECREASES, air pressure

DECREASES

As the water vapor in air (humidity) INCREASES, air density

DECREASES

Air pressure changes with

DENSITY, ALTITUDE, TEMPERATURE, HUMIDITY

warm air mass results in:

Faster particle movement; Particles farther apart; Lower density because less mass in a set volume; RESULTS IN LOWER AIR PRESSURE.

effects of altitude increasing

Gas particles become fewer and more spread-out; There is less mass within a set volume, so air density decreases; Because there is less mass of air pushing down, air pressure decreases as you go upwards in the atmosphere.

As air humidity DECREASES, air density INCREASES and air pressure

INCREASES

As air temperature DECREASES (gets colder), air density

INCREASES

As air temperature DECREASES , air density INCREASES and air pressure

INCREASES

As altitude DECREASES, air density INCREASES and air pressure

INCREASES

As altitude above Earth's surface DECREASES, air density

INCREASES

As the density of air INCREASES, air pressure

INCREASES

As the water vapor in air (humidity) DECREASES, air density

INCREASES

cold air mass results in:

Slower particle movement; Particles closer together; Higher density because more mass in a set volume; RESULTS IN HIGHER AIR PRESSURE.

Dry Air

With little or no water vapor molecules in air, the humidity of air is very low; As the humidity of air decreases, the density of air increases and air pressure becomes higher.

altitude

air pressure decreases as altitude increases.

millibars (mb)

air pressure units recorded by an aneroid barometer.

air pressure is greatest...

at the surface

aneroid barometer

barometer that is a cylinder with an internal spring; All air is removed, so cylinder is a vacuum; A needle and gauge on the outside are connected to the spring to record changes in air pressure; Increase in air pressure compresses the cylinder and spring resulting in the needle moving CLOCKWISE; Decrease in air pressure expands the cylinder and spring, resulting in the needle moving COUNTER CLOCKWISE

(cold or warm) air is associated with high air pressure.

cold

Air pressure __________ as altitude increases

decreases

Air pressure is greatest closer to the surface where the air is

denser

in mercury barometer, mercury _______ to indicate decrease of air pressure

falls

pressure

force acting on a set area

What force keeps 99% of the gases in the atmosphere close to Earth's surface?

gravity

barometer

instrument used to measure changes in air pressure

Air containing water vapor has ____ mass than dry air.

less

humid air is ____ dense and exerts a ______ air pressure than dry air.

less

Air pressure is lower, high in the atmosphere where the air is

less dense

Warm air is __________ than cold air.

less dense

Cold air is __________ than warm air.

more dense

air pressure

pressure caused by the weight of the atmospheric gases pushing down on the surface of the Earth OR any object in the atmosphere.

in mercury barometer, mercury _______ to indicate increase of air pressure

rises

inches of mercury (Hg)

the height of the column of mercury when using a mercury barometer.

In which layer of the atmosphere are most of the gases found?

troposphere