1. 5.01 Heating and Cooling of the Atmosphere
Meteorology
5.01 Heating and Cooling of the Atmosphere
References:
FTGU pages 123, 124, 136 and 137

2. 5.01 Heating and Cooling of the Atmosphere
MTPs:
Vertical Structure
Composition
ICAO Standard Atmosphere
Temperature Scales
Atmospheric Properties
Atmospheric Density
Temperature Differences
Heating and Cooling

3. Vertical Structure Troposphere Stratosphere Weather happens here
To 25,000 – 30,000 feet over poles
To 55,000 – 65,000 feet over equator
Temperature decreases with height
Stratosphere
Troposphere to 170,000’
Temperature increases with height

4. Vertical Structure Mesosphere Stratosphere to 270,000’
Temperature decreases with height, to -85°C
Thermosphere
Tops at 1.1 million to 2.6 million feet ( kilometres)
Temperature increases with height, up to 1,500°C
Exosphere
Mainly comprised of hydrogen and helium
Extends into space

5. Vertical Structure

6. Vertical Structure Label the layers of the atmosphere!
Choose from these:
Stratosphere
Thermosphere
Exosphere
Troposphere
Mesosphere

7. Composition The atmosphere is made up of a mixture of gases
Nitrogen (78%)
Oxygen (21%)
Other (~1%) (Argon, CO2, Water Vapour etc.)
Although water vapour is less than
1% of the atmosphere, it remains
the most important component
from the standpoint of weather,
based especially on its ability to
change state

8. ICAO Standard Atmosphere
The International Civil Aviation Organization (ICAO) Standard Atmosphere:
Sea Level for North America
Based on summer and winter averages at 40°N latitude
The Standard:
MSL pressure of 29.92” Hg ( hpa)
MSL temperature of 15°C
Air is a “perfectly dry gas”
Lapse rate of 1.98°C per 1000 feet

9. Temperature Sun heats earth, earth heats atmosphere
Celsius (nearly worldwide):
Freezing point of water: 0°C
Boiling point of water: 100°C

10. Atmospheric Properties
Mobility
The ability for air to move
Atmosphere like an “ocean of air”
Wind like “streams of water”
(Much more freedom of
movement with air than water)
Compression
Air is compressed as it descends into greater pressure
Occupies less space

11. Atmospheric Properties
Expansion
As air rises, it reaches areas of lower pressure, causing it expand and cool
This cooling can be enough to condense water vapour in the air, forming cloud
This is why clouds and precipitation are common in areas of rising air
From a meteorological standpoint, the most important property of the air!

12. Atmospheric Properties
Density - mass per unit volume
Cold air is dense:
Molecules are move slowly and
are packed close together
Heavier and tends to sink
Warm is less dense:
Molecules are moving rapidly
taking up more space (or less
molecules in the same space)
Warm air is lighter and is pushed up by the cold air

13. Atmospheric Density Density Relationships: Density vs. Temperature:
Indirectly proportional
Density vs. Humidity:
Density vs. Pressure:
Directly proportional

14. Confirmation Questions
1. What is the most important property of the atmosphere?
2. If the density of the air increases, what happens to the pressure?
3. What gas makes up the majority of the atmosphere?
Nitrogen 78%

15. Temperature Differences
Horizontal Temperature Differences
Diurnal Variation
Seasonal Variation – earth’s tilt
Latitude- north pole versus equator
Topography
Land and water differences
Clouds
Clouds reflect large amounts of solar radiation
At night, clouds trap the heat radiated off the earth

16. Atmosphere Heating Types of Atmospheric Heating: Radiation (heating)
Earth absorbs sun’s
short wave radiation
The lower atmosphere
is then heated by the earth

17. Atmospheric Heating Conduction
If two substances are in contact, heat will flow from the warmer to the colder substance
Air is a poor conductor, so this usually only occurs in small layers
Same as the heat transferred when roasting marshmallows

18. Atmospheric Heating Convection
Air heated through conduction becomes buoyant and rises
This air then heats the air in the upper atmosphere

19. Atmospheric Heating Advection (heating)
Occurs when cold air moves over a warm surface and its lower layer is heated by conduction

20. Atmospheric Heating Turbulent Mixing
Turbulent air mixes a warmer surface layer of air with an unheated air aloft, spreading the heat upward

21. Atmospheric Heating Compression
As air descends it compresses due to increased pressure and therefore heats up

22. Atmospheric Cooling Advection cooling Lower levels only
When air is cooled by moving over a colder surface
Cooling occurs as a result of conduction between air and surface
Some mechanical turbulence can aid in spreading cooling effect

23. Atmospheric Cooling Expansion cooling
The most important cooling process of the air
Air forced to rise experiences lower pressure and is allowed to expand
This expansion causes decrease in temperature

24. Confirmation Questions Name 2 types of atmospheric heating
Name 2 types of atmospheric cooling
Describe how the earth is heated and cooled through radiation.
Which layer of the atmosphere contains all weather?

25. Soaring