119
edits
Changes
From CUGC Wiki
→Atmosphere
== Atmosphere ==
We rely on the atmosphere to survive, or, more importantly, to fly gliders. This section discusses some approaches to model the atmosphere and its properties at different altitudes. To be specific, we are interested in the static pressure distribution at different locations, which depends, according to the Equation of State, on the density and the temperature.
=== Simplified model ===
It is understood that a large pressure is present in the depth of the ocean. The same applies to the atmosphere: we are living at the bottom of an ocean of air.
Think about the ocean. You may know already from the science class that the water pressure comes from the weight of all the water above the location of interest. If you dive into the water you will feel the pressure, which originates as a result of a large amount of water directly on top of you resting its weight on you. Water pressure is given by (you will hopefully remember this from school):
\[p=\rho_{water} g H\]
Where \(g\) is the gravitational acceleration.
Air is not different. If we do the opposite and fly to high altitudes, because the amount of air resting on us is less (we have moved onto the top of a significant amount), the pressure will reduce. The formula to quantify this is:
\[p= p_{ground} -\rho_{air} g H\]
Where \(p_{ground}\) is the static pressure on the ground. This simple formula allows us to relate the decrease in static pressure to the altitude we are at, if we know the density of air and the gravitational acceleration (which we do).
=== Compressible effects ===
