WHAT GOVERNS THE WAY THAT GASES, IN OUR ATMOSPHERE, BEHAVE?

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CHARLES’ LAW

Molecules of gas at a fixed pressure andtemperature, vibrate sufficiently to

occupy a fixed volume

CHARLES’ LAW

Increased molecularvibration, spacing

increases

CHARLES’ LAW

Volume Increases

increases

CHARLES’ LAW

Cool Warm

Volume Increases

increases

CHARLES’ LAW

Cool Warm

Volume Increases

increases

Decreased molecularvibration, spacing

decreases

CHARLES’ LAW

Cool Warm

Volume IncreasesVolume Decreases

increases

decreases

CHARLES’ LAW

Cool Warm

increases

decreases

CHARLES’ LAW“If the atmospheric pressure is held constant, hot gases expand to occupy

a bigger volume and cold gases contract to occupy a smaller volume.”

Cool Warm

increases

decreases

V=k2.TAt constant Pressure

CHARLES’ LAW

Cool Warm

increases

decreases

V↓=k2.T↓ V↑=k2.T↑

CHARLES’ LAWV=k2.T

At constant Pressure

M =1.0

BOYLE’S LAWMolecules of gas at a fixed pressure and

temperature, vibrate sufficiently tooccupy a fixed volume

M =1.0

BOYLE’S LAW

Atmospheric Pressure

Vibrating molecules of gas

M =1.0M = 0.5

M = 1.0

BOYLE’S LAWCompress,squeeze, add“weight”

M = 0.5

M =1.0M = 0.5

M = 1.0

BOYLE’S LAWCompress,squeeze, add“weight”

Decompress,relax, reduce“weight”

Increased PressureVolume contracts

Decreased PressureVolume expands

M = 0.5

M =1.0M = 0.5

M = 1.0

“At constant temperature, the pressure exerted on a gas is inversely related to the volume the gas occupies – gases are compressible.”

BOYLE’S LAW

M = 0.5

M =1.0M = 0.5

M = 1.0

P↑ ….. V↓P↓…. V↑

BOYLE’S LAWP = k1/V

At constant Temperature

HOW ARE THESE LAWS GOING TO HELP TO MOVE MASS AND ENERGY IN THE ATMOSPERIC SYSTEM?

Air Filled Balloon

EQUAL PRESSURE (ATMOSPHERIC)

HigherPressure

LowerPressure

Air Flow

Differences in pressures causemotion of the air

Air temperature ≈ Sensible heat fluxfrom insolation= f(latitude,season)

Air temperature ≈Sensible heat fluxfrom insolation= ∫ (latitude,season)

Changes in temperaturecause changes in volume

occupied by air.

P = k1/VAt constant Temperature

occupied by air.

Changes in volume occupiedcause changes in pressure on

occupied by air.

Differences in pressure causemovements within the

atmosphere

occupied by air.

Temporal and spatialdifferences in insolationrelated to pressure that

moves atmosphere

Differences in pressure causemovements within the

atmosphere

THE EQUATION OF STATE FOR AN IDEAL GAS.

PUTTING IT ALL TOGETHER!

P = R. ρ. T

P = Pressure on a gasR = Gas Constantρ = Density of gasT = Temperature of gas

P = R. ρ. T

P = Pressure on a gasR = Gas Constantρ = Density of gasT = Temperature of gas

P = R. ρ. T

P = Pressure on a gasR = Gas Constantρ = Density of gas: ρ = Mass/VolumeT = Temperature of gas

P = R. M/V. T

P = Pressure on a gasR = Gas Constantρ = Density of gas: ρ = Mass/VolumeT = Temperature of gas

P = R. M. T V

Charles’ Law: Fixed P, T and V directly related

9 = 1. 1 . 2.25 0.25

9 = 1. 1 . 3.0 0.33

If T rises to 3.0, thenV must rise to 0.33 toKeep P constant at 9!

P = R. M. T V

Boyle’s Law: Fixed T, P and V inversely related

3. 3 = 1. 1. 9 4. 2.25 = 1. 1. 9

V . P = R. M. T

Multiply bothsides by V

Pressure declinesso volume occupiedincreases to keep T constant

P = R. ρ. T

PRACTICAL APPLICATION

We know that Atmospheric Pressure declines with altitude, so what can weexpect to happen to Temperatures and the Density of the air as you climb a mountain or go up in an airplane?

P = R. ρ. T

Should become colder and the atmosphere “thinner”!

P = R. ρ. T

Normal Lapse Rate: Rate at which temperatures decline (increase) with increase (decrease) in altitude

P = R. ρ. T

Normal Lapse Rate: Rate at which temperatures decline (increase) with increase (decrease) in altitude

6.5°C per Kilometer3.6°F per 1000 ft.

4.392 km

-13°C

WHAT GOVERNS THE WAY THAT GASES, IN OUR ATMOSPHERE, BEHAVE?

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