Download Low Clouds

….A Tricky Business
Overview
1. Terrain Factors
2. Turbulence
3. Normal Weather Patterns
Terrain Factors
 The presence of mountain ranges change the
characteristics of a front.
 As air masses enter the United States the mountains
cause them to rise.
 Along many seacoasts there is a breeze from the sea
by day. This moist, relatively cool air rises and heats
as it passes across land.
 Convectional clouds form and bring afternoon
showers. (Gulf Coast)
Mountain Wave Turbulence
Altimeter
 An altimeter is essentially a
barometer measuring air
pressure returning altitude
influenced by:
 Temperature
 Pressure Fronts
Turbulence
 Thermal Turbulence
• Intense surface heating causes
convection currents.
• More intense convection currents
occur over dark-colored ground.
• Less convection currents will be
over light-colored ground.
• Because velocity varies turbulent
conditions are expected.
Turbulence
 Thermal Turbulence
• Presents the biggest problem for aviators during landing.
• To eliminate during normal flight, climb above clouds.
• When cumulus clouds are present, convection currents and
thermal turbulence exists.
Turbulence
 Mechanical Turbulence - Low Level
• Results from strong wind gusts over
rough terrain or manmade features.
• Produces turbulent eddies below 500
feet.
Turbulence
 Mechanical Turbulence - Wake
Turbulence
• Caused by aircraft flying
through air.
• Presents a major hazard to
another aircraft following
too close.
• Most hazardous during
landings and takeoffs.
Turbulence
 Wind Shear - Low Level Wind Shear (LLWS)
• Occurs below 10,000 feet.
• Primarily caused by frontal systems, low level jet
streams and thunderstorms.
• Occurs rapidly.
Turbulence
 Wind shear - Clear Air
Turbulence (CAT)
• Occurs above 15,000 feet.
• Not restricted to clear skies.
• Turbulence occurs in vicinity
of upper level jetstream.
Climatic Provinces
Normal Weather Patterns
 Hawaii
• Two major factors determine
weather.
 Dramatic heights and
contours of land areas.
 Prevailing northeast trade
winds.
• Pleasant temperatures.
• Little distinctions between
summer and winter.
Normal Weather Patterns
 Alaska
• Has several different kinds of weather.
• No great extremes in southern part of state.
• Arctic slope lies in northern part of state.
• Broad valley and low mountain ranges.


Continental weather.
Temperatures from -70o F in winter to 90o F in summer.
Summary
1. Terrain Factors
2. Turbulence
3. Normal Weather Patterns