1. Clouds D. Blanck

2. Water, Energy and Temperature  Gas - water vapor (invisible)  Liquid - water droplets (visible)  Solid - ice crystals, hail, snow  Gas - water vapor (invisible)  Liquid - water droplets (visible)  Solid - ice crystals, hail, snow

3. What are clouds? Clouds are formed of tiny droplets of water or ice. (~20 microns in diameter) Necessary ingredients for cloud formation: 1. Humidity 2. Rising, expanding, cooling air Adiabatic expansion/cooling 3. Condensation nuclei Clouds are formed of tiny droplets of water or ice. (~20 microns in diameter) Necessary ingredients for cloud formation: 1. Humidity 2. Rising, expanding, cooling air Adiabatic expansion/cooling 3. Condensation nuclei

4. How is air cooled?  Contact with a cold surface such as over land in winter.  Convection: uplift over warm ground.  Orographic: air rising over mountains.  Frontal: a mass of warm air meeting and rising over a mass of cold air.  Contact with a cold surface such as over land in winter.  Convection: uplift over warm ground.  Orographic: air rising over mountains.  Frontal: a mass of warm air meeting and rising over a mass of cold air.

5. What happens when air is cooled?  Relative humidity increases.  Dew point is reached (100% relative humidity).  Water vapor (invisible) condenses to form water droplets (visible).  Sometimes the water vapor may change straight into solid state: called sublimation.  Relative humidity increases.  Dew point is reached (100% relative humidity).  Water vapor (invisible) condenses to form water droplets (visible).  Sometimes the water vapor may change straight into solid state: called sublimation.

6. Clouds can be classified by their shape and height Flat clouds eg Stratus (St) Fluffy clouds eg Cumulus (Cu) Wispy clouds eg Cirrus (Ci) Cloud shapes

7. Clouds can also be classified by height of cloudbase Low level (below 2000m) eg stratus Middle level - alto (2,000 to 6, 000m) eg alto-cumulus High level - cirro (above 6,000m) eg cirrus Cloud heights

8. Cloud Diagram

9. Specific Cloud Examples Cirrus Whispy, fibrous, feathery. Calm clear day. Made up of ice crystals Predict approaching storms

11. Cirrostratus “tangled web” Halo effect

13. Cirrocumulus Tiny balls of cotton, Also called a “mackerel sky,” fish scales.

15. Altocumulus Great flock of sheep

17. Altostratus Sun shines through, frosted glass

19. Stratocumulus Twisted cotton

21. Stratus-Nimbostratus Formless, blanket like cloud Nimbus = RAIN

23. Some clouds develop vertically Cumulus Fluffy, cottonball appearance Generally fair weather clouds

25. Cumulus Congestus or Towering Cumulus

26. Cumulonimbus Storm clouds. Currents of rising air meet tropopause Anvil head appearance. Thunder and lightning

29. Other clouds Lenticular cloud “UFO” shape

31. Scud cloud Ragged stratus cloud usually associated with Cumulonimbus.

32. Fog A cloud at ground level

33. Noctilucent clouds

34. Spot the cloud! Low and flat ….. Stratus

35. Spot the cloud! Middle level, fluffy ….. Middle level, fluffy ….. Alto -Cumulus

36. Spot the cloud! High level, wispy ….. High level, wispy ….. Cirrus

37. Spot the cloud! Rain bearing, storm clouds ….. Rain bearing, storm clouds ….. Cumulo-Nimbus

38. World cloud patterns Can you explain the major world cloud belts?

39. Clouds in Forecasting