why does vne decrease with altitude?
160149
The lower air density at altitude means the rotor is biting into less dense air, so to get the same performance a higher angle of attack (more collective) is required. The rotor system will therefore suffer retreating stall at a lower airspeed than it would at sea level. Hence the reduction in VNE.
530832
Atmospheric pressure decreases as the height of a surface above ground level increases. This is because, as the altitude increases: the number of air molecules decreases. ... there is less air above a surface.
435700
As the pressure decreases with altitude, the parcel of air expands against the reduced external pressure. It does work in doing so, which reduces its internal energy, the average energy of its constituent molecules. The definition of temperature is molecular kinetic energy. When this is lower, temperature is lower.
1024198
Because the amount of oxygen carried to the muscles by a given volume of blood is limited at altitude, this is compensated by increasing cardiac output (=stroke volume * heart rate). During the first few hours/first day at altitude, heart rate is increased (stroke volume is decreased) during rest and submaximal work.
159897
Although the decreased blood pressure following exercise has mainly been found to be due to a decreased vascular resistance, the underlying cause for this decreased resistance has not yet been determined. It is unlikely that PEH is the result of thermoregulation or changes in blood volume.
1104533
So, usually, as the altitude or elevation increases, the weather gets colder and in fact the climate becomes naturally harsher with more intense weathering such as windier and colder. Furthermore, there is also less air as the altitude or elevation increases.
897396
Really? "Historically, standard vertical separation was 1,000 feet from the surface to FL290, 2,000 feet from FL290 to FL410 and 4,000 feet above this. This was because the accuracy of the pressure altimeter used in aircraft to determine level decreases with height."
198673
The atmosphere is the most dense near the surface because of gravity. As one goes higher, the air gets thinner and thinner. At an altitude of about ten kilometers, the atmosphere is only half as thick as at the surface. ... When water evaporates from lakes and oceans, it turns into a gas and becomes part of the atmosphere.
1054694
The problems associated with high altitude are usually only manifest in people who have been to altitudes in excess of 3,000 metres (10,000 feet). Cold: is a factor generally experienced at altitude. As a rule, the higher you climb, the colder it gets.
717443
The atmosphere is the most dense near the surface because of gravity. As one goes higher, the air gets thinner and thinner. At an altitude of about ten kilometers, the atmosphere is only half as thick as at the surface.
755313
You can calculate your own visual descent point (VDP), since one isn't provided for you, by taking the height above touchdown (600 ft. in this case) and dividing it by 300 ft/NM. This gives you 2.0 miles from the runway. Since the chart shows the runway threshold at 0.2 DME, your VDP will be at 2.2 DME.
487884
Most recipes are designed to be prepared at low altitudes. ... called for in the recipe. High-altitude recipes use less baking powder than is needed at sea level, as the decreased air pressure causes gases in foods to expand faster. Baking powder is 20 percent more effective at 5,000 feet than it is at sea level.
462950
If the partial pressure increases, then the DO concentration in water will also increase. When the altitude is increasing, the total atmospheric pressure decreases, and then the partial pressure of oxygen is also decreasing (assuming a constant proportion of O2 in air).
579582
Air molecules colliding with a surface cause atmospheric pressure. ... Atmospheric pressure decreases as the height of a surface above ground level increases. This is because, as the altitude increases: the number of air molecules decreases.
1303884
Greenhouse gases absorb heat at relatively low altitudes and warm the surface--but they have the opposite effect in higher altitudes because they prevent heat from rising. In a cooler stratosphere, ozone loss creates a cooling effect that results in further ozone depletion.
972222
Atmospheric drag at orbital altitude is caused by frequent collisions of gas molecules with the satellite. It is the major cause of orbital decay for satellites in low Earth orbit. It results in the reduction in the altitude of a satellite's orbit.
365136
Vx is the slowest (IAS), and is the Maximum ANGLE of climb. It allows one to climb to altitude within the shortest horizontal distance. Vy is slightly faster, and is the Maximum RATE of climb. It allows one to climb to altitude in the shortest time.