Weather Theory COPY Flashcards
What is Low Pressure Mean?
1) Baqd Weather
2) Pressure is higher than standar 1013 hPA/22.92
3) Air is Less Dense
4) Air will rise and will reach cold air
5) COndensate and clouds will form
How high Pressure Occur?
1) Air becomes colder
Pressure is higher than standar 1013 hPA/22.92
3)Air is more dense. Air will fall down and more stable
What is the wind direction in Low pressure area and HIgh Pressure area?
Low Pressure: Counter Clock
High Pressure: Clock direction
What is a Front?
- A boundary between air masses having different temperature and moisture content.
- Often a “line of confrontation” with serious flying hazards.
- When you cross it, weather will change.
What to expect on Cold Front?
- Colder air slips beneath and overtakes warmer air.
- Cold Air is coming
- Wind speed is higher
- The leading edge of a cold air mass overtakes and replaces warmer air at the surface. Cold fronts generally move faster and have a steeper slope than warm fronts.
In a cold front, explain the: Winds/clouds/precipitation
Temperature decrease; by a wind shift from a southerly to a northwesterly direction; and, on occasion, by gusty winds.
Convective clouds often develop in the warm air ahead of the front.
The warm and wet ground behind the front generates low-level convection and fairweather cumulus in the cold air.
Fast-moving cold front
Very steep slopes and narrow bands of clouds, usually found ahead of the front.
Showers and thunderstorms develop along the surface position, and a line of thunderstorms (squall line) frequently develops ahead of the front.
What is the cause of Slow-moving cold front?
Less steep slopes and cloud systems that may extend far to the rear of the surface position of the front.
What to expect from warm Front?
- Warmer air rides above and overtakes cooler air.
- Possible Thnderstorms
What to exepct from occluded front?
1) When the cold front overtakes warm front
2) Thunderstorms
3) Other event depending on air temprature
What is stationary front?
1) Front doesn’t move
2) A lot of Rain
What is a Wind Chart? and read the follwoing:
What is the direction of the wind?
From top of the flag and direction got he poll.
From 90 to 270
What is a Significant Weahter Chart?
forecasts of weather conditions at specified valid times.
What is the Standard TIme and Daylight savings time in Florida?
4 Hours in Daylight Saving
5 Hours in Standard
CHANGES IN OUR ATMOSHERE OCCUR BECAUSE OF THE______
CHANGES IN OUR ATMOSHERE OCCUR BECAUSE OF THE SUN
Atmosperic Pressire in Millibars and Inches of mercury
Standard Pressure of 29.92 inches of mercury and also as 1013.2 millibars of pressur
What is “Convective Heating and Cooling.”?
TEMPERATURE RISES WHEN HOT AND FALLS WHEN COOL
The density of air has significant effects on the aircraft’s performance because as air becomes less dense, it reduces
- Power because the engine takes in less air.
- Thrust because a propeller is less efficient in thin air.
- Lift because the thin air exerts less force on the airfoils.
Effect of Pressure on Density
Since air is a gas, it can be compressed or expanded. When air is compressed, a greater amount of air can occupy a given volume.
If the pressure is doubled, the density is doubled; if the pressure is lowered, the density is lowered.
Effect of Temperature on Density
Increasing the temperature of a substance decreases its density. Thus, the density of air varies inversely with temperature. This statement is true only at a constant pressure
Effect of Humidity (Moisture) on Density
Water vapor is lighter than air; consequently, as the water content of the air increases, the air becomes less dense, increasing density altitude and decreasing performance.
What is a RIdge and Trough and Ridge?
Elongated area of high pressure is called a “Ridge
Elongated area of low pressure is called a “Trough”
What is an Isobar? How to interpert?
Isobars and Pressure Gradients Difference in pressure create WIND.
The closer the isobars the higher the winds.
Which direction does the wind move?
High Pressure to Low Pressure
Convective currents cause the bumpy, turbulent air sometimes experienced when
flying at lower altitudes during warmer weather. On a low altitude flight over
varying surfaces, updrafts are likely to occur over pavement or barren places, and
downdrafts often occur over water or expansive areas of vegetation like a group of
trees. Typically, these turbulent conditions can be avoided by flying at higher
altitudes, even above cumulus cloud layers.
What is a Convective Current and when do they occur?
- localized vertical air movements, both ascending and descending.
- Convective currents are most active on warm summer afternoons when winds are light.
- Because of uneven heating, the strength of convective currents can vary considerably within short distances.
- Extend several thousand feet
What does a Convective currents cause?
turbulence, especially at low altitudes.
Explain the Following
Turbulence on approach can cause abrupt changes in airspeed and may even result in a stall at a dangerously low altitude. To prevent the danger, increase airspeed slightly over normal approach speed.
What is the mountains connection with the winds?
While the wind flows smoothly up the windward side of the mountain and the upward currents help to carry an aircraft over the peak of the mountain, the wind on the leeward side does not act in a similar manner.
As the air flows down the leeward side of the mountain, the air follows the contour of the terrain and is increasingly turbulent.
What are the Effect of Obstructions on Wind and Why is it important for the pilots?
1) Obstructions on the ground affect the flow of wind and can be an unseen danger.
2) Ground topography and large buildings can break up the flow of the wind and create wind gusts that change rapidly in direction and speed. T
What is a Valley Breeze and Mountan Breeze?
Look the the picture and remeber the SUN heating/
Explain the following
What is a radiation Fog?
- forms in low-lying areas on clear, calm, humid nights
- in stable air associated with high pressure systems.
- Dissipates with rising sun.
What is an Advection Fog?
- Warm moist air moving over a cooler surface Wind is required to form advection fog.
- Up to 15Kts intensifies, above lifts to form stratus clouds.
Explain the follwoing:
Updraft
Mature Stage
Dissipating Stage
