The adiabatic atmosphere obeys the equation P/ p k =constant where k is a constant and is density. If the temperature decreases 0.38C for every 100 ft increase in altitude, what is the value of k?...

The adiabatic atmosphere obeys the equation

P/ p^k
=constant

where k is a constant and is density. If the temperature decreases 0.38C for every 100 ft increase in altitude, what is the value of k? [Note: Air is an ideal gas; g = 32.2 ft/s2 ; R = 1544 ft lbf /(8R lb mol)].