A 100 Km long tube of ideal gas (molecular mass equivalent to argon) is perfectly insulated from the outside environment. At the bottom of this tube, it is 20C with a pressure of 100 KPa. This tube is affected by the same 10 m/s^2 gravitational acceleration throughout. I have no idea of how to calculate what the pressure and temperature is at the top of this long tube. Can anyone offer a formula and work out a solution based on the variables given?