Weather Flashcards
What are the standard temperature and pressure values for sea level?
- 15C or 59F
– 29.92” Hg or 1013.2 mb
Discuss isobars. What does it mean when the isobars are close together?
Isobars connect equal lines of pressure.
Closely spaced isobars means that there is a strong pressure gradient and winds will be strong.
How do surface winds flow in relationship to isobars? Why? Winds aloft?
At the surface, winds flow at an angle to the isobars because of surface friction.
Aloft, winds from more or less parallel because of the Coriolis force.
What type of clouds, visibility and precipitation would you expect from stable air?
stratiform clouds, poor visibility, smooth air, steady or continuous precipitation
What type of clouds, visibility and precipitation would you expect from Unstable air?
Cumuliform clouds or clouds with vertical development, good visibility, turbulence, and showery precipitation
What are the general characteristics of low/high pressure areas?
Low – Cyclone – counterclockwise and rising air
High – Anti Cyclone – clockwise and descending air
What is a ridge? Trough?
Ridge – extended area of high pressure – descending air
Trough – extended area of low pressure – rising air
What must be present in order for a thunderstorm to form?
- Unstable Atmosphere
- Lifting Action
- Sufficient Moisture
What are the stages of a thunderstorm?
- Cumulus (Updrafts)
- Mature (Updrafts + Downdrafts)
- Dissipating (Downdrafts)
What is wind shear? Why is it an operational hazard?
Rapid change in wind direction or velocity
It can cause dramatic changes in indicated airspeed and causes severe turbulence within the shear zone
What is wind shear? Why is it an operational hazard?
Rapid change in wind direction or velocity
It can cause dramatic changes in indicated airspeed and causes severe turbulence within the shear zone
What does dew point mean?
The temperature at which the air becomes saturated
Discuss the types of fog. Advection, Radiation, Upslope, Precipitation-Induced
Advection: moist warm air moves over colder land or water
Radiation: forms on clear nights with little or no wind and only over land
Upslope: moist unstable air is cooled as wind pushes it up a slope
Precipitation Induced: warm rain falls through cool air. Evaporation from the rain
saturates the cool air and fog forms.
What is induction icing?
This includes any icing that impedes that process of air entering the intake manifold to be mixed with fuel. Ice that builds up on the air intakes is an obvious form of this.
Carburetor ice is also a form of induction icing.
This can be attributed to the incomplete vaporization of fuel in combination with the pressure decrease inside of the
venturi. Even on a day as warm as 70°F, carburetor ice can began to form with adequate moisture in the air.
What is Instrument Icing?
Icing of the pitot tube or static ports can cause the instruments to give inaccurate readings or to fail completely.