How Atmospheric Stability Determine The Movement Of Aircraft


Presentation Description

Few things that you need to consider before you go for a flight and complete training always ensures that you are thoroughly taught about the various elements of flying an aircraft.


Presentation Transcript

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How Atmospheric Stability Determine The Movement Of Aircraft Atmospheric stability is primarily identified as the atmospheric resistance towards vertical motion. In a stable atmosphere you will experience a resistance to an upward movement or downward movement. In unstable atmospheric conditions you will experience a growing vertical current due to an upward or downward disturbance. In order to determine atmospheric stability one needs to measure the difference of rate of ambient temperature lapse a specific air parcel with that of dry adiabatic rate constant 3°C/1000 ft lapse rate. A layer or parcel of stable air would be accompanied by an inversion in temperature. On the other hand warming from below would result in a decrease in air mass stability. Stable air is identified by stratiform clouds including fog while unstable air comprises of cumuliform air. In the stable air you will experience constant precipitation while in unstable air conditions you might get a showery form of precipitation. Stable air features smooth air movement and unstable air mostly features turbulent air conditions. In the stable air you get fair or almost poor visibility with hazy and smoky surroundings. But in the unstable air conditions you experience better visibility except for the presence of blowing obstructions. Most people flying an aircraft would agree that a stable air condition is undoubtedly better than an unstable one especially for flying without facing much trouble. In short it can be said that due to stability vertical motion is hindered and vertical motion is greatly promoted due to instability. Some amount of instability is still acceptable especially if you are a

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glider pilot. As without some amount of instability the thermals will not form. You can determine the stability or instability in the air with the moisture in the air. With moist air and deeper instabilities you can expect to experience some amount of hazards and thunderstorms. This is why it is said to be highly important to maintain a record of the atmospheric conditions before you are out on a flight. Usually in a stable and dynamic system there is a displaced element air parcel that has to get back to its original position. In an unstable dynamic system the displaced element accelerates further from its original position. However in a neutrally stable system displaced element is neither restored to its original position nor does it accelerates from its existing position. Firstly you need to assume that the air is totally dry and it’s forced to rise. It expands because of falling pressure and cools down. In contrast a dry air parcel is compressed and is forced to go down because of growing pressure as well as warmth. Without any heat transfer between ambient air surrounding and dispatched parcel the process that takes place is known as adiabatic. A stable atmosphere can go haywire under two circumstances: ● The air parcel is warmed up by more than 2°C more than 22°C. In that case the layer by 3000 ft will be unstable in the second condition. Therefore if the temperature on air aloft is stable then warming of the lower layers will lead to instability and this causes better thermal development. ● If air is cooler at 3000 ft the layer will be unstable. Therefore in this case if the ground temperature is same then cooling aloft will result in instability and develop improved thermal soaring. If temperature aloft as well as the surface remains the same by similar amounts then the layer has an unchanged stability. Lastly if the aloft is the same while there is cooling in the surface then there is greater stability in the layer. These are the few things that you need to consider before you go for a flight and complete training always ensures that you are thoroughly taught about the various elements of flying an aircraft. Resource: movement.html

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