Meterology

• Atmosphere
• Clouds
  • Four basic types
  • Low clouds
  • Middle clouds
  • High clouds
  • Clouds with vertical development
• Fog
• Fronts
• Turbulence
  • Low level turbulence
• Clear Air Turbulence
• Mountain Wave Turbulence
• Structural Icing
  • Rime icing
  • Clear icing
  • Mixed icing

    Atmosphere

Clouds

Four basic types

• Stratus: sheet like clouds
• Cumulus: puffy clouds
• Cirrus: wispy clouds
• Nimbus: rain clouds

Low clouds

• Surface to 6,500 feet AGL
• Usually consist entirely of water but sometimes ice as well
• Types
  • Stratus
  • Stratocumulus
  • Nimbostratus

Middle clouds

• 6,500 AGL to 20,000 AGL
• Composed of water, ice crystals or supercooled water
• Types
  • Altostratus
  • Altocumulus

High clouds

• Above 20,000 AGL
• Generally are white and gray
• Form in stable air
• Types
  • Cirrus
  • Cirrostratus
  • Cirrocumulus

Clouds with vertical development

• Cumulus
• Towering Cumulus
• Cumulonimbus

Fog

• Radiation, or Ground Fog
  • Forms in moist air over low, flat areas on clear, calm nights with relatively little to no wind
• Advection Fog
  • Warm, moist air blows from the south and comes in contact with cool moisture on the ground, forming fog
• Upslop Fog
  • As moist wind blows toward a mountatin, it rises up and cools down, forming fog
• Steam Fog
  • Cold, dry aira moves over warm water. As water evporates and forms fog.
  • Commonly associated with low-level turbulence and icing
• Ice Fog
  • Forms in cold weather when water vpor forms directly into ice crystals
  • Typically in arctic regions

Fronts

• Cold front
  • Cold air advances and replaces warm air
• Warm front
  • Warm air advances and replaces cold air
• Stationary front
  • When the cold air and warm air are relatively equal, there will be little to no movement
• Occluded front
  • When warm air gets caught bewteen two cold air masses
    

Turbulence

Low level turbulence

• Caused by surface heating or friction (less than 15,000 MSL)
• Mechanical:
  • Winds blowing around hangars, trees, buildings
• Convective:
  • As solar radiation heats the ground during the morning and afternoon generating thermals that move away from the ground, creating chaotic patterns
  • When moisture present, towering cumulus clouds indicate a presence of convective turbulence
• Frontal:
  • The lifting of the warm air by the sloping frontal surface and friction between warm airmass and cold airmass produce turbulence in the frontal zone
• Wave Turblence
  • Wing tip vortices are created when an airplane generates lift

Clear Air Turbulence

• Normally above 15,000 ft MSL
• Associated with wind sheer, a sudden change of wind velocity and/or direction.

Mountain Wave Turbulence

• When strong winds blow across a mountain range and when air is stable

Structural Icing

Rime icing

• Brittle and frost-like, easy to remove
• Its irregular shape and rough surface make it very effective in reducing lift and increasing drag

Clear icing

• Hard and glossy, difficult to remove

Mixed icing

• Hard, rough conglomerate, hard to remove