1. CLOUD FORMATION

2. CLOUDS FORM WHEN: What is a cloud? Air rises Air cools Air condenses
A group of tiny water drops or ice formed around a bit of dust or salt
Clouds form when the dew point is reached!
Air rises
Air cools
Air condenses
CLOUDS FORM WHEN:

3. 4 ways that air rises

4. Convection How do clouds form from convection?
When air is moist, upward flowing air currents cause cloud to form

5. Orographic lifting
Air

9. Orographic lifting How do clouds form from orographic lifting?
• Orographic lifting -- mountains act as barriers to the flow of air, forcing the air to move upward

10. Frontal lifting/wedging
Cold
Air
Warm
Air

11. Frontal lifting/wedging
What is a front?
a boundary or edge where two air masses meet
How do clouds form from frontal lifting?
Frontal lifting -- warmer, less dense air, rises above the cooler air, causes condensation and storms

12. Convergence
Air
Air

13. Convergence How do clouds form from convergence?
Convergence -- air masses with the same temperatures crash into each other and both rise

14. Temperature Inversion
When air found at lower levels is actually cooler than the air above it
it is more dense so it stays below
This can happen on a cool night - land cools quickly, causing the air above it to cool as well

15. Temperature inversions can create smog in cities with high pollution (polluted air stays low and blankets city)

16. Summary: Cloud Formation Mr. Fetch's Earth Science Class
AIR
CONDENSES
AIR RISES
AIR COOLS
Convection
Orographic Lifting
Frontal Lifting
Convergence
By expanding
Cools to the dewpoint and water vapor condenses.
Mr. Fetch's Earth Science Class
Mr. Fetch’s Earth Science Classroom

17. CLOUD CLASSIFICATION

18. Clouds are classified by….
Shape
Height

19. Write your description of each type!
Shapes of Clouds
Stratus…
Cumulus…
Cirrus…
Nimbus…
Write your description of each type!
Three types by appearance
Stratus – layered or blanket the sky
Cumulus – Puffy; often flat bases and lumpy tops
Cirrus – Wispy, feathery, composed of ice crystals
Nimbus – rain

20. Heights of Clouds
Height is determined by where the base of the cloud is
High (cirro-)
Middle (alto-)
Low (strato-)
Base

21. High Clouds High altitude clouds are made of ice crystals due to…?
Cirrus
Cirrostratus
Cirrocumulus

22. Cirrus Clouds
Cirrus
Cirrostratus – Very thin layer of clouds with a wispy or fibrous appearance; sometimes produces a halo
Cirrocumulus – Small rippled clouds

24. Cirrostratus Clouds
Cirrostratus – Very thin layer of clouds with a wispy or fibrous appearance; sometimes produces a halo

26. Cirrocumulus Clouds
Cirrocumulus – Small rippled clouds

27. Middle Clouds
Middle clouds are made of ice crystals and water droplets
Altocumulus
Altostratus

28. Altocumulus
Altocumulus – Puffy clouds that may occur between 6500 and feet

30. Altostratus
Altostratus – Layered cloud sheets; thin enough to allow some sunlight through.

32. Low Clouds Low clouds are made of water droplets Cumulus Stratus
Stratocumulus
Nimbostratus (rain cloud)
Nimbostratus – Grey, dreary looking clouds
Stratus

33. Cumulus

35. Stratus

37. Stratocumulus
Stratocumulus – Low cumulus clouds, formed from weak convective currents

39. Nimbostratus
Nimbostratus - grey, dreary clouds

41. Cumulonimbus Clouds (thunder clouds)
Very tall clouds, extending to the tropopause (top often shaped like an anvil)
Intense weather:
lightning & thunder
hail
tornadoes
heavy rain

43. Fog Fog is a cloud with its base on the ground, caused by…
Air cooling and draining into low areas (ex: river valleys), where fog develops
Cool air moves over warm water (ex: lakes), causing moisture to evaporate from the water

47. Strange Cloud Formations
YouTube:
Strange Cloud
Formations