Weather Theory Flashcards
Test on Weather Theory
What percentage of the Earth’s Atmosphere is made up of Oxygen?
21
True/False. The Anvil of a thunderstorm indicates the direction of storm movement.
True
rue/False. Airflow circulates clockwise (anti-cyclonic) around a Low Pressure System.
False
What are the different types of icing an aircraft can encounter in-flight.
Clear Ice, Rime Ice, Mixed.
True/False. An Occluded Front typically develops when a faster moving cold front catches up to a slower moving warm front.
True
Downdrafts in a microburst can be as strong as…
6,000 FPM and cause headwind losses of 30-90 knots.
What are the different cloud classification types.
High (Cirrus), Middle (Alto), Low (Stratus), and Clouds with Vertical Development.
True/False. In an Inversion, temperature increases with altitude to a certain point.
True
True/False. Coriolis Force is caused by the rotation of the Earth and it deflects airflow to the right in the Northern Hemisphere.
True
Where is Advection Fog most commonly found?
Coastal Areas
True/False. Standard Pressure at Sea Level = 29.92 and Standard Temperature = 15C.
True
What are the stages of a thunderstorm.
Cumulus, Mature, and Dissipating Stage
rue/False. A Squall Line is a narrow band of active thunderstorms.
True
In which layer of the atmosphere do most aircraft operate?
Troposhere
True/False. The Standard Adiabatic Lapse Rate = -2C per Thousand Feet of Altitude gain.
True
What is the Earth’s atmosphere made of and what is the percentage of each.
Nitrogen 78%
Oxygen 21%
Argon, carbon dioxide and traces of other gases 1%
How does air flow in a low pressure system?
Counter clockwise (cyclonic) and up. Hint: Right hand thumbs up: Makes a backwards L for Low pressure, fingers show counter clock wise and thumb points up.
How does air flow in a high pressure system?
Clockwise (anticyclonic) down and out.
Hint: Right hand thumbs down: Fingers point clockwise, thumb pointed down for down flow.
What is an Occluded Front?
A faster moving cold front catches up to a slower moving warm front.
What is a microburst?
Low level wind shear.
What is Coriolis Force caused by?
The rotation of the Earth.
What direction(s) does Coriolis Force deflect airflow?
Right in the Northern Hemisphere. Left in the Southern Hemisphere.
Name the Standard Pressure and temperature at sea level.
Standard pressure at seal level is 29.92 (1,013.2 mb)
Standard temperature is 15C or 59F
What is a squall line?
A narrow band of active thunderstorms.
The Standard Adiabatic Lapse Rate is equal to what?
-2c per thousand feet of altitude gain. (In the Troposphere)
What is above the Troposphere?
The Tropopause.
What is weather?
It is the state of the atmosphere at a given time and place with respect to variables, such as temperature, moisture, wind velocity, visibility, and barometric pressure.
What is the atmosphere?
A blanket of air made up of a mixture of gases (in constant motion) that surrounds the Earth.
How far does the atmosphere reach?
Almost 350 miles from the surface of the Earth.
How high does the troposphere extend.
(0-12 KM) 7 Miles. Can change seasonally and reach as far as 4-12 miles over the northern and southern poles and up to 48000ft over equatorial regions.
How does the temperature change in the Tropopause?
It stays fairly constant.
What is the purpose of the Tropopause?
It is a boundary that traps moisture and associated weather in the troposphere.
What is the height of the Tropopause?
It varies depending on height of the Troposphere.
Areas of low pressure exist over the equatorial regions and areas of high pressure exist over the polar regions due to what?
Due to difference in temperature.
High pressure air likes to flow where?
Into low pressure areas.
Within how many feet of the ground does friction between the surface and the atmosphere slow moving air?
2,000 FT
Can wind direction on the surface vary from a few thousand feet above and why?
Yes. Wind is diverted from its path because of the friction between the surface and atmosphere.
Atmospheric pressure can also be reported in what?
Millibars. 1 Hg is equal to approximately 34 mb
1 Hg is equal to what?
Approximately 34 mb
Standard seal level pressure in millibars is what?
1,013.2 mb
How does atmospheric pressure change as altitude increases?
On average, with every 1,000 ft of increase in altitude, the atmospheric pressure decreases 1”Hg (34mb)
What is the typical mb pressure readings range?
950.0 to 1,040.0
Does density altitude effect aircraft performance and if so, how?
Yes. High density altitude means worse performance. This is because the aircraft thinks it is working at a higher altitude than it actually is. Low density altitude causes the aircraft to preform better as it thinks that it is operating at a lower altitude.
What is convection/ convective currents?
Upward and downward motion of air.
What is wind?
Horizontal motion.
How do Sea and Land Breezes work?
Day: Cool air over the water sinks (higher pressure) flows toward low pressure warm air over land, and rises. Air continues in that pattern. This is the same idea for Night breezes, only the water would be warmer and the land cooler.
Can convective Currents create turbulence?
Yes.
How is turbulence created?
Uneven heating (areas of rock, sand, barren land vs areas of green and water) creates small areas of local circulation called convective currents. Convective currents cause bumpy turbulent air when flying at lower altitudes during warmer weather.
How does wind flow on each side of the the mountain?
Nice and smooth on the windward side but turbulent on the lea-word side.
What is wind shear?
Drastic change in wind speed and or direction in a very small area. Windshear can subject an aircraft to violent up and down drafts as well as horizontal movement.
What type of windshear is the most hazardous?
Low-level windshear.
What is Low-level wind shear commonly associated with?
Passing frontal systems, thunderstorms, temperature inversions, and strong upper level winds.