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What is the approximate air pressure at 5 miles above sea level?(1) 1.0 atmospheres (3) 0.4 atmospheres

(2)0.7 atmospheres (4) 0.2 atmospheres

Air PressureIs measured with a barometer.

Uses millibars (mb) or inches (in) as unit.

Will change with altitude (where more? less?)

Is a result of the density (weight) of air.

Can we change airs density?

heat

Cool, so liquid is compact.Hotter, so liquid expands.How DOES a thermometer work? Add HEAT energy, so molecules move more!

Increasing VolumeIncreasing temperature and heat energyAirs density (pressure) tends to increase as(1) temperature increases

(2) temperature decreases

(3) weather becomes wetter

(4) temperature variesAir Pressure Differences

Dry Air (mostly N2 & O2)

Moist Air (more H2O less N2)Which weighs more?Which is less dense?

A barometric pressure of 1021.0 millibars is equal to how many inches of mercury?

(1) 29.88 (3) 30.25

(2) 30.15 (4) 30.50

COLD AIR!DRY AIR!Dense

WARM AIR!MOIST AIR!Less dense

Heat airLet air cool

COLD AIR!DRY AIR!DenseTends to sinkWARM AIR!MOIST AIR!Less denseTends to riseDo you remember how to boil water?

Hot, less dense, risesCold, more dense, sinks

?HLSinkingCurrentRisingCurrentConvection in the Atmosphere

Air not only rises or sinks, it also moves naturally from where there is more (H) to where there is less (L).

HLSinkingCurrentRisingCurrentWINDNo vapor up here, so sinking air tends to be dry!Vapor comes from water on surface, so rising air is moist!

Low Pressure:

Air enters (converges)

Warm

Moist/Humid

Low density

Rises/Floats

BAD WEATHER!High Pressure:

Air Leaves (diverges)

Cold

Dry

High density

Sinks

NICE WEATHER!Air pressure is usually lowest when the air is

(1) warm and dry(2) warm and humid(3) cool and dry(4) cool and humid(1) Earths rotation and unequal heating of Earths surface

(2) Earths revolution and unequal heating of Earths surface

(3) Earths rotation and Suns gravitational attraction on Earths atmosphere

(4) Earths revolution and Suns gravitational attraction on Earths atmosphereThe planetary wind belts in the troposphere are primarily caused by theFoucaults pendulumOrhow to kill lots of people

Coriolis EffectObjects moving on Earths surface rotate with the Earth.

Objects not attached to the Earth will not rotate with the Earth.

These objects will be deflected from their intended path.

In the Northern Hemisphere, wind and water deflect to the right!The diagram shows a box used to demonstrate the process of convection in the atmosphere.

Which diagram has arrows that show the direction of airflow that occurs when thecandle is burning?

Hurricanes

Tornadoes

A Foucault pendulum appears to change its direction of swing over a period of several hours because of Earths(1) rotation

(2) tilted axis

(3) revolution (4) gravity

Low Pressure

Air is rising, converging and rotating counter-clockwise

Actual Low Pressure SystemsHigh Pressure

High Pressure air is sinking, diverging and rotating clockwise

Which is Which?

1)2)

LLLLWhich map best represents the surface wind pattern around a Northern Hemisphere LOW pressure center?

Earth rotates below, so by the time the cannonball hits the ground the target has moved! Which table correctly indicates the name of the weather instrument and the weather variable that it measures?

The diagram shows weather instruments A and B.What is the approximate air pressure at 5 miles above sea level?(1) 1.0 atmospheres (3) 0.5 atmospheres

(2)0.7 atmospheres (4) 0.2 atmospheresAir pressure is usually highest when the air is

(1) cool and humid(2) cool and dry(3) warm and humid(4) warm and dry

Lets gomeasure!

Still confused?

Dry Air (mostly N2 & O2)

Moist Air (more H2O less N2)What happens to the density of air as it gets more humid?It decreases! (water vapor weighs less than Oxygen & Nitrogen)

What happens to the density of air as it gets hotter?It decreases! (heat increases volume, decreases density)

Air pressure (density) can change!Hot air is lower density Cold air is higher density

Wet air is lower density Dry air is higher density

Hot air is low pressure Cold air is high pressure

Wet air is low pressure Dry air is high pressure

What air pressure is normal for aHot summer day?Low Pressure

Sunny (dry) day?High Pressure

Cold winter day?High Pressure

Rainy day?Low Pressure

How can I make a barometer?

WaterAirPressure

Too high!Too Poison!

Just right!Aneroid barometer

What will happen to reading from hereto here?