Chapter 4 Flashcards
How many knots does a full sock indicate?
15 knots
When is a Gust reported?
A gust is reported when there is at least 10 kn variation between peaks and lulls within the last 10 minutes
What does the letter V stand for in a metar?
Variable of the wind direction
Can you assume that there is no clouds above 15,000 feet if it says CLR IS?
No, there could be a cloud layer above it
What happens if the temperature and dew point are close together?
Less visibility
Low-pressure winds go in what direction?
Counterclockwise
Winds are always ________ to isobars ?
Parallel
Velocity = ?
Wind speed
What instrument do you use to measure wind?
Anemometer
What is the definition of a Lull?
Between the gust and your steady
What three forces effect wind or air motion?
Pressure gradient
Coriolis force
Friction force
Where will you find the boundary layer?
2,000 AGL
At what place do you find most of the friction or frequent turbulence?
The boundary layer
Where will you find a deeper boundary level?
higher wind speeds
A seabreeze comes from what direction?
Wind coming from the sea
What direction does the wind come from during a land breeze?
Wind comes from the land
At what time will you see a land breeze?
Night
At what time will you see a seabreeze
Day
When is there a frontal passage?
A frontal passage occurs during a change in pressure.
When pressure decreases and then increases what does this represent?
A frontal passage
“VV” stands for ?
Vertical visibility
Is vertical visibility considered a ceiling?
Yes
In the southern hemisphere wind rotates in what direction?
90° clockwise
In the northern hemisphere what rotates in what direction?
90° counterclockwise
What direction does a cyclone flow?
Counterclockwise to the right
what direction does an anti-cyclone flow?
Clockwise to the left
What force makes the wind want to go outward 90° to the right in the northern hemisphere and 90° left in the Southern Hemisphere?
Coriolis effect
If you are observing frontal activity what type of chart are you looking at?
A surface chart
Why is the wind skewed in surface charts?
Because of friction
When two air masses come together energy transfers creating what?
Weather
What does Coriolis effect need to work?
Wind
If the wind speed is zero, what is Coriolis speed at?
Zero
Friction is caused by high-pressure wanting to go ______ and low pressure wanting to go ________.
Outward and inward
What type of performance do you get with windshear?
An increase in performance
What type of changes do you see in wind sheer?
Instantaneous
On approach if you have a tailwind what kind of performance will you have?
A decrease in performance
If you have a headwind on approach what kind of performance will you have?
An increase in performance
Where is the lull in this metar :
33010G24K
10G
At what degree does variable wind have to be at to be present on a metar?
Greater than or equal to 60 degrees
What are the two causes of wind?
Pressure gradient and wind variation
What are the two types of wind?
Horizontal and vertical
Are cold fronts gradual or steep?
Steep
What is it called when air is being sucked up due to low-pressure
Convergence
What is it called when air is being sucked down due to high pressure
Divergence
What is it called when warm air moves upward over the cold air?
Frontal lifting
Gravity wave motions are typical in what state of air neutral, unstable or stable?
Stable
What is dry adiabatic process?
Cooling by expansion and warming by compressing