quiz 1 Flashcards
100
Composition of the earths dry atmosphere is about
21% oxygen,78% nitrogen and 1% other gases
Air is never completely dry,it contains near 0 to what % of water vapor
5%
The transition zone between the lowest layer of the atmosphere and the layer above it is
called the _______________________________. This transition zone acts to trap most
of the water vapor in the _______________________________.
Tropoause
Troposphere
ISA stands for
International standard atmosphere
. In the ISA, the sea-level temperature and pressure is _______oC, ______oF and
___________”Hg, ___________ mb(hPa).
15
59
29.92
1013.2
At the lower levels of the ISA, the temperature decreases at ______oC per 1,000’ of
altitude increase, and the pressure drops ______”Hg per 1,000’ of altitude increase
2
1
The standard temperature at 10,500 MSL is _______oC
-6
The standard temperature at 25,000 MSL is _______oC
-35
_________________ ___________________ is the cause of most weather
phenomena
Temp variation
T/F Temperature is a major factor in determining aircraft performance
T
The Earth receives energy from the sun in the form of solar radiation. In turn, the Earth
radiates energy back out into space thru ____________________
_____________________.
Terrestrial radiation
Two commonly used temperature scales are __________________ and
_____________________.
Celsius and Fahrenheit
What are the conversion formulas for Celsius and Fahrenheit?
oC =
oF =
5/9(F-32)
9/5C+32
Convert 25 degrees F to C
-3.5
Which scale is always used to report temperatures aloft and on the ground in aviation
weather reports and forecast?
Celsius
When heated, air Expands / Contracts. When cooled, air Expands / Contracts
Expands
Contracts
Explain why you would see higher temperature variations in dry arid inland environments
as compared to coastal environments.
Water is much more resistant to temp change and warms up or cools down areas around it faster or slower
Why does the amount of solar radiation received vary by region?
seasons,latitude,topography and altitude
. An ________________________ often develops near the ground on clear, cool nights
when wind is light which causes the temperature to increase with height.
inversion
_____________ absorbs and radiates heat much faster than ___________________.
Land
Water
The instrument designed for measuring atmospheric pressure is the _______________________
Barometer
Two commonly used pressure units are _____________________ and ____________________
inches of mercury hg
hectopascal hPa
The standard pressure at mean sea level is ____________ or _____________________.
- 29 in
1013. 25 md
Pressure varies primarily with ___________________ and ________________________
Altitude
temperature
Station Press” is the pressure measured at ___________________________________________
field elevation
Within the lower few thousand feet of the troposphere, the pressure decreases roughly _____ per
______-foot increase in altitude; therefore the ISA pressure at 7,500’ MSL is _______.
1in
1000
22.42
The rate of decrease of pressure with height in warm air is ______________than standard, and the rate
of decrease of pressure with height in cold air is _________________than standard
less
greater
The higher we go, the slower / faster is the rate of decrease with height.
slower
What are isobars?
lines that plot sea level pressure on a map
A LOW is
area of pressure surrounded on all sides by high pressure
A HIGH is
surrounded on all sides by low pressure
A TROUGH
enlongated area of low pressure
Low-pressure systems are often are regions of______________ flying weather, while high-pressure
systems are often regions of _____________ flying weather.
poor
favorible
True altitude is the distance above ______________ _______________ ___________
MSL
Indicated Altitude is ______________________________________________
altitude above mean sea level when set to local
While flying, barometric pressure drops .75”Hg. You fail to adjust your altimeter setting. Once you arrive
to your destination you would be _______feet higher / lower than your intended altitude.
750 lower
Pressure Altitude is __________________________
Pressure altitude is the height above a standard datum plane (SDP), which is a theoretical level where the weight of the atmosphere is 29.92 “Hg (1,013.2 mb) as measured by a barometer.
You can determine pressure altitude by setting your altimeter to the standard altimeter setting of
_______ in the window.
29.92
When descending through 18,000 feet MSL you must _________
set altimeter
Pressure altitude is 8000 feet. Temperature is 76F. What is the density altitude?___________
11,000
Describe how high density altitude affects aircraft performance
reduces power because there is less air and less propeller grip,less thrust and lift
Hypoxia may affect night vision at altitudes as low as ______
5000
Differences in atmospheric pressure are caused by differences in _____
Temp
The horizontal air flow in a convective current is called ________
wind
Closely spaced isobars mean ___________________________ whereas widely spaced isobars mean
_________________________.
strong winds
light winds
Explain Coriolis Effect. _______
air moving across the surface of the earth seems to be deflected by rotational forces
Because of the Coriolis effect, in the northern hemisphere the wind around a High moves
Clockwise / Counterclockwise, and the wind around a Low moves Clockwise / Counterclockwise
clockwise
counterclockwise
Generally, as a rule of thumb, if you are flying on a cross country flight in a left crosswind, you are flying
toward an area of ___________________ weather.
Bad
Why are the winds in a hurricane so strong? _____
very low pressure
At the surface, ____________________ causes the wind to flow at an approximate 30o angle to isobars
friction
A Jet Stream is a band of winds meandering through the atmosphere at a level near the
tropopause
Where is wind shear normally found?
two different wind masses moving at different speeds
What is the primary danger of wind shear?
turbulance
