When an aircraft passes through a thick cloud, there would be a significant pres

Question

When an aircraft passes through a thick cloud, there would be a significant pressure difference on the upper and the lower surfaces of he aircraft. This pressure difference results in a force acting on the aircraft, thus altering its altitude. This is a disturbance and the aircraft must be able to reject the disturbance, else its altitude may be affected. A more common disturbance is the turbulent current and this results in a disturbance force acting on the aircraft. It will results in a slight bumpy if the aircraft has good controller to reject it, else the flight can be bumpy.

Explanation / Answer

ans:- The pressure difference created due to cloud on the upper and lower part of the aircraft can be overcome by providing pressure control disturbance.

Since heat does not leave the affected air mass, this change of pressure is adiabatic, with an associated change of temperature. In humid air, the drop in temperature in the most rarefied portion of the shock wave can bring the air temperature below its dew point, at which moisture condenses to form a visible cloud of microscopic water droplets. Since the pressure effect of the wave is reduced by its expansion (the same pressure effect is spread over a larger radius), the vapor effect also has a limited radius.

Such vapor can also be seen in low pressure regions during high–g subsonic maneuvers of aircraft in humid conditions.The same kind of condensation cloud is sometimes seen above the wings of aircraft in a moist atmosphere. The top of a wing has a reduction of air pressure as part of the process of generating lift.

This reduction in air pressure causes a cooling, just as above, and the condensation of water vapor. Hence, the small, transient clouds that appear.

Lightning occurs when an electrical charge is built up within a cloud, due to static electricity generated by supercooled water droplets colliding with ice crystals near the freezing level. When a large enough charge is built up, a large discharge will occur and can be seen as lightning .

So you need two things for lightning to occur- a charge buildup in a place and a charge gradient (difference in charge, like between two clouds or cloud to surface) for lightning to occur.

Based on this, there is little chance of any charge buildup and discharge in the condensation over wings- it is too short lived for any charge buildup within itself and the charges over the aircraft wings are dissipated by the static wicks in the trailing edges- so no chance of 'cloud' to wing surface either.

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