Cumulus Clouds

• puffy, “popcorn-like” clouds

• cumulus humilis (humble):

  • fair weather

  • small

• cumulus congestus (heap):

  • towering cumulus clouds

    • heating causes vertical updrafts

    • air parcels cool as they rise

    • excess water vapor condenses

    • latent heat released

    • causes more updrafts

Thunderstorms

• cumulonimbus:

  • thunderstorm cloud

  • very large (tall), thick clouds

• thunderstorm = cumulonimbus clouds with lightning and thunder (and commonly rain)

• top of cloud is near top of troposphere

• base of cloud is near the ground

• strong updrafts and downdrafts (turbulent)

• looks like a mushroom or an anvil (well-developed)

  • anvil can be 10s of mile in diameter

• if very strong updrafts, then the dome of the cloud overshoots above the anvil

• storm energy from temperature and humidity

Thunderstorm Occurrence

• more commonly occur in:

  • tropical locations: abundant sunshine (heat) and moisture

  • late afternoons in the summer: most surface heating

• also in regions with convergent winds and/or lifting

  • mountains

  • land/sea boundary

Thunderstorm Fuel

• need constant inflow of warm, moist air or they die out

• most thunderstorms use up fuel (warm, moist air) and choke on their exhaust (cool, dry air)

• last only a half hour to an hour