Obviously, the local atmospheric conditions affect the airplane. Air density and the wind speed are the most important conditions. Other conditions, such as pressure and temperature, affect some of the instruments.
The Standard Atmosphere model
gives the average
temperature, pressure, and density (over time) at any point in the
atmosphere, as a function of altitude. For altitudes less than
36000 ft, the average temperature as a function of altitude (which is
an empirical formula) is:
Unlike density, there is no standard model for wind; it is (almost) entirely dependent on the weather. Again, a meteorological model can be used. In the absence of a meteorological model, the user could simply input a velocity vector for the wind he or she wants to fly in (this could be useful to practice landing in a crosswind, for instance).
Some types of wind are easily predictable and not much dependent on the weather. For example, thermal updrafts and downdrafts occur over specific locations at specific times of day.