1. Chapter 11 section 3
vocabulary

2. Condensation nuclei
Small particles in the atmosphere around which cloud droplets can form.

3. Orographic lifting
When wind encounters a mountain and the moving air has no where to go but up—this warmer moist air forms clouds when it hits the colder air above.

5. stability
The ability of an air mass to resist rising. This occurs when the air mass is cooling. (if it is warming it wants to rise)

6. Latent heat
Energy stored in water (energy is transferred between water and the atmosphere)

7. Coalescence
When cloud droplets collide and make larger droplets

8. precipitation
When water (liquid or solid) falls to earth

9. Water cycle
Constant movement of water between the atmosphere and Earth’s surface

10. Evaporation
The process of water changing from a liquid to a gas

11. Types of clouds
Cirro = high
Alto = middle
Strato = low

12. Types of clouds Cirrus = hair Cumulus = pile or heap Stratus = layer
Nimbus = cloud (think rain)

13. Clouds are classified by what vertical level their bases (or bottoms) form at:
Low Clouds:
Middle Clouds:
High Clouds:

14. Low Clouds:
Low clouds can be on the ground (fog) to ~6,000’ above the surface.
6,000 ft above ground
Five low cloud types:
Cumulus
Stratus and Fog
Stratocumulus
Nimbostratus
Cumulonimbus
Lyndon State
Green Mountains

15. Cumulus: Heaped or lumpy looking, most commonly
portrayed type in art, film
Stratus: Layered or flat
looking and grayish
Stratus

16. Stratocumulus: looks both lumpy and layered, flatter than
cumulus but more lumpy than
stratus
Fog: when a stratus cloud
touches the ground
Fog

17. Nimbostratus: a stratus cloud that's precipitating – rain
and/or snow is falling from
the cloud and reaching the
ground
Cumulonimbus: a cumulus
cloud that has precipitation
falling from it and
reaching the ground
Cumulonimbus
*Nimbus = precipitating

18. Middle Clouds: Middle clouds can extend from ~6,000’ to ~20,000’ above
the surface.
~20,000 ft above ground
Two basic middle cloud types “Alto” prefix:
Altocumulus
Altostratus
6,000 ft above ground
Green Mountains
Lyndon State

19. Altocumulus: look like cotton balls, about the size of your
fist or smaller if you extend
your arm and look towards
them
Altostratus: layered and flat,
but higher than stratus
Altostratus

20. High Clouds:
High clouds can extend from ~20,000’ to 40,000’ above the surface.
~40,000 ft above ground
Three basic high cloud types “cirro” prefix:
Cirrus
Cirrostratus
Cirrocumulus
~20,000 ft above ground
6,000 ft above ground
Lyndon State

21. Cirrus: appear wispy in pieces or small patches, not organized
in sheets
Cirrostratus: wispy - especially
on the edges, flat and fairly
white, organized in sheets or
layers
Cirrostratus

22. Cirrocumulus: fairly rare, look like small cotton balls, about
the size of your pinky when
you extend your arm and look
at the cloud elements.
Cirrocumulus

23. Special Clouds
Contrail: short for “condensation trail” – forms when water from air plane
exhaust forms clouds behind the plane
Contrail
Lenticular: type of mid-level cloud
Produced by airflow over terrain,
frequently mistaken for UFOs
Lenticular

24. Lenticulars over the Salt Lake Valley

25. Cloud Classification

26. How do clouds form?
Clouds for when warm, moist air rises, expands and cools in a convection current.
As the air reaches its dew point, the water vapor in the air condenses around the condensation nuclei

27. What are Condensation Nuclei ?
Small particles in the atmosphere around which cloud droplets can form
Ex. Salt, dust, pollen, bacteria, ash

28. How do clouds form? Cont.
Clouds for when warm, moist air rises, expands and cools in a convection current.
As the air reaches its dew point, the water vapor in the air condenses around the condensation nuclei.
When millions of these droplets collide – a cloud forms.

29. Collision of AIR MASSES= CLOUDS
As warm air moves into the area, it will be forced to rise over more-dense cold air. As the warm air cools, the water vapor in it condenses and forms a cloud.

30. How are clouds formed by Orographic Lifting?
Clouds can also form when wind encounters a mountain and the air has no place to go but up. The effect is the same as with any rising air- it expands and cools.

31. Topic 7 - Weather

32. Weather Definition
Weather – state or condition of the variables of the atmosphere at a given time
Weather variables – temperature, air pressure, wind, moisture, cloud cover, precipitation, storms
Weather occurs in the troposphere (lower layer of the atmosphere)
Heat energy (insolation) is what drives weather

33. Temperature
Reminder: use page 13 on ref. table to convert temperatures
Three Scales: Fahrenheit, Celsius, Kelvin
Isotherms – lines that connect equal lines of temperature

34. Heating the Atmosphere
More insolation = higher temperatures
Conduction moves heat – Earth’s surface to the atmosphere
Absorption of insolation by gases and aerosols
Absorption of infrared radiation given off by Earth’s surface
Condensation and (sublimation) gives off stored heat
Coriolis Effect – due to rotation and winds friction between air and Earth’s surface

35. Another Important Heat Transfer
Convection – due to differences in density
Convection Currents – air moving in circular patterns

36. Expansion and compression
When a gas expands its temperature decreases
When a gas compresses its temperature increases
Air rises expands and cools
Air sinks compresses and warms