Progress Test 3 Flashcards
(36 cards)
True or False? All forecasts and reports for wind is given in magnetic heading.
False. Reports and forecasts are given in relation to True Heading.
Does wind direction reports show where the wind is going to or coming from?
Where the wind is coming from.
Aerodrome reports and forecasts show the wind at what level?
Surface Level.
Why does ATC provide wind direction in relation to magnetic heading?
Because the runway heading is magnetic.
What are wind gusts?
Short periods of increased wind speed, this can effect the handling of the aircraft and a very slight increase of airspeed will be required.
Wind socks come in a variety of sizes, when the wind speed reaches the size of the sock what will happen?
The wind sock will become horizontal, the wind speeds can then be estimated knowing the size of the sock and it’s angle of which it is positioned against the wind.
What is the friction layer?
The friction layer is when the wind comes in contact with the Earths surface and is slowed down by friction.
At what altitude is it considered to be free of the friction layer?
2, 000ft. However, at sea this can be as low as 50ft and as high as 5, 000ft over land on a gusty day.
How much surface friction at sea is there compared to land?
Over the sea the surface speed can be 80% of the 2000ft wind speed.
Over land the surface speed can be 50% of the 2000ft speed.
Is the Coriolis Force increased or reduced near the surface and why?
The Coriolis effect is reduced at the surface due to the decrease of wind speed.
What is the effect of the Coriolis Force at sea level to wind bearing?
As the Coriolis force is less at surface level there is less of a right turn so the bearing of the wind reduces closure to the surface.
What is the effect of the Coriolis Force at sea level over land and sea?
Over land the wind can back by 30 to 40 degrees compared to the wind direction at 2000ft.
Over the sea the wind can back by 10 degrees compared to the direction of the wind at 2000ft.
What is backing?
Reduction is wind bearing.
What is Veering?
Increase in wind bearing.
Name three characteristics if sea/land breeze.
- Not found above 1000ft
- Limited to around 10kts
- Usually effected by the Coriolis effect resulting in up to an angle of 30 degrees to the shoreline.
What does Diurnal mean?
The difference between day and night.
What is the effect of the Diurnal Effect during the day. (Northern Hemisphere)
The sun heats the land causing convection currents which results in the mixing of wind at the surface and the upper winds. Leads to stronger winds in the day compared to night.
This results in the wind Backing less as there is less of a difference between the surface wind and the upper wind. The surface wind will Veer compared to Night time winds.
What is the effect of the Diurnal Effect during the night. (Northern Hemisphere)
The land radiate the heat more which cools the surface quicker.
Little convection takes place so there is less mixing of wind aloft and surface wind, leading to weaker winds at the surface.
The Coriolis Effect is reduced so the surface wind will Back more compared to the daytime wind.
Results in less turbulence.
What are Katabatic winds?
This occurs when the surface of the mountains and hills radiates their warmth and cools down. The cool dense air descends down the slope due to Gravity, slopes amalgamate (combine together) into a valley creating gale force like winds (can have the name Mistral). Occurs in the evening or the first part of the night.
What are Anabatic winds?
This occurs when the surface of a hill or mountain slope gains heat and the layer of the air above the slopes heats up. The warm air ascends up the hill. This creates more light winds since the warm air is working against the gravity.
What occurs when there is a greater pressure differential?
Creates Strong Winds, the shorter the distance of the pressure differential the stronger the winds.
What is a way of expecting strong winds and how should you determine when to fly?
If the pressure drops by more than 1hpa an hour for more than 12 hours strong winds will be expected. Should not fly in winds that are more than half the speed of the stall speed.
Strong winds creates turbulence at low levels, how does turbulence cause airframe stress?
Can cause damage due to the sudden changes in lift, drag, acceleration and deceleration forces.
What is Vno speed?
The maximum cruise speed in rough air.
