Cloud Flashcards
Describe the relationship between stability of air and cloud type.
- Air from the equator traveling poleward = stable/low cloud
- Because decreasing surface temperature cools it
- Air from the poles traveling to the equator = unstable
- Because increasing surface temperature warms it
Describe the relationship between stability of air and cloud type.
- Air from the equator traveling poleward = stable/low cloud
- Because decreasing surface temperature cools it
- Air from the poles traveling to the equator = unstable
- Because increasing surface temperature warms it
Describe the relationship between stability of air and cloud type.
- Stable clouds = Cirrostratus, Altostratus, Nimbostratus, Stratocumulus, Stratus
- Unstable clouds = Cirrocumulus, Altocumulus, Cumulonimbus, Towering Cumulus, Cumulus
List the vertical extents of the three main cloud layers in the mid-latitudes.
- High cloud = 17,000 to 45,000ft
- Mid cloud = 7,000 to 23,000ft
- Low cloud = below 7,000ft
List the vertical extents of the three main cloud layers in the tropical latitudes.
- High cloud = 20,000 - 60,000ft
- Mid cloud = 7,000 - 25,000ft
- Low cloud = Below 7,000ft
State the difference between the Lifting Condensation (LCL) and the Convective Condensation Level (CCL)
- LCL = Height non-convective cloud forms when forced up
- Forced up by fronts, gills, turbulence, convergence
-CCL = Height convective cloud forms (thermal)
-Raises temperature further away from dew point
Therefore CCL is always higher than LCL
Demonstrate the use of the simple formulae to calculate the LCL and CCL.
- CCL = 400 x (surface temperature - dew point)
- LCL = 400 x (surface temperature - dew point) x 0.85
Describe the cirrus cloud.
- White
- High level
- Fibrous hair-like
- Narrow bands
- Stable
- Ice crystals
Describe the cirrocumulus cloud.
- White
- High level
- Sheet cloud
- Ripples
- Conditional instability
- Ice crystal
Describe the cirrostratus cloud.
- White
- High level
-Transparent - Only cloud to create solar halo
- Stable
-Ice crystals
Describe the altocumulus cloud.
- White/grey
- Mid level
- Unstable
- Droplets/ice crystals
Describe the altostratus cloud.
- Grey/blue
- Mid level
- Sun barely visible
- Stable
- Droplets/ice crystals
Describe the nimbostratus.
- Grey/dark
- Mid level (bases can be low level)
- Conditional instability
- Droplets/snow/Super cooled water droplets (SCWD)
- Thick
- Often form along warm or occluded fronts
- Form through the deepening and thickening of an altostratus.
Describe the stratocumulus cloud.
- Grey/white
- Low level
- Rolled layer cloud
- Stable
-Droplets
Describe the stratus cloud.
- Grey
- Low level
- Layer cloud
- Stable
- Droplets
Describe the cumulus cloud.
- White
- Low level
- Heaped cloud
- Conditional instability
Describe the cumulonimbus cloud.
- Very dark
- Low level
- Heaped cloud
- Large vertical extent
- Anvil on top
- Unstable
Describe typical conditions for each of the 10 main cloud types with respect to turbulence.
- Cirrus = nil
- Cirrostratus = nil
- Cirrocumulus = light
- Altostratus = light/moderate
- Altocumulus = light/moderate
- Nimbostratus = moderate
- Stratocumulus = light
- Stratus = nil
- Cumulus = moderate/severe
- Cumulonimbus = moderate/severe
Describe typical conditions for each of the 10 main cloud types with respect to icing.
- Cirrus = nil or trace
- Cirrostratus = nil or trace
- Cirrocumulus = nil or trace
- Altostratus = light
- Altocumulus = light
- Nimbostratus = moderate/severe
- Stratocumulus = light/moderate
- Stratus = light
- Cumulus = moderate
- Cumulonimbus = moderate/severe
Describe the typical conditions for each of the 10 main cloud types with respect to precipitation.
- Cirrus = nil
- Cirrostratus = nil
- Cirrocumulus = nil
- Altostratus = light/moderate
- Altocumulus = light/moderate
- Nimbostratus = heavy precipitation
- Stratocumulus = drizzle/light
- Stratus = drizzle/light
- Cumulus = heavy showers
- Cumulonimbus = heavy showers
Outline the atmospheric conditions of an Asperitas.
- Unstable
- Severe turbulence
- Occurs within Altostratus and Stratocumulus
- Most likely cause is gust front
Outline the atmospheric conditions of a Mammatus.
- Unstable
- Severe turbulence
- Forms under Cb
Outline the atmospheric conditions indicated by altocumulus lenticularis.
- Ragged edges indicate turbulence
- Formed from mountain waves above mountain height
Outline the atmospheric conditions indicated by rotor clouds.
- Forms under Lenticular clouds
- Strongest turbulence in first wave
Outline the atmospheric conditions indicated by Kelvin Helmholtz waves.
- Caused by vertical windshear.
Outline the atmospheric conditions indicated by Altocumulus Castellanus.
- Unstable
- Cumuliform tops rising from a common base
- Moderate turbulence
Outline the atmospheric conditions indicated by banner cloud.
- Uplift of cloud on sheltered lee side
- Reduced pressure downwind
Explain the cloud dispersal processes of direct warming.
- Direct solar radiation disperses cloud from top down
- Terrestrial radiation increases surface temperature
- Moves dew point partner away from temp dispersing cloud
Explain the cloud dispersal processes of sinking of air.
- Adiabatic warming as pressure increases
- Dew point moves away from temperature
Explain the cloud dispersal processes of mixing with clear air.
- Injects dry air (entrainment)
- Lowers relative humidity causing evaporation
Describe the effect of latent heat release on stability inside a cloud and its influence on the resulting cloud type.
- Releasing latent heat increases temperature
- Increases instability
- Results in Cumuliform cloud or Cb
With regard to orographically developed cloud, explain the influence of stability/instability and different surface dew point values on the type and vertical extent of any cloud formed.
- Stable = shallow vertical extent (stratus)
- Unstable = Deep vertical extent (cumulus)
- Closer dew point is to surface temperature further away = lower cloud base
With regard to orographically developed cloud describe the formation and characteristics of lenticular clouds.
- Formed due to mountain waves.
- Lens shaped clouds
- Found above mountain tops in crests of waves
- Can be found up to and above tropopause
