This piece represents thermal soaring. Hawks use thermals to gain thousands of feet of altitude in order to travel downwind. Hang glider pilots and sailplane pilots use these same upward forces to gain altitude and fly cross-country. Every day in aircraft people experience this natural phenomenon as turbulence. When you core a thermal doing 360 degree turns and reach the absolute height possible in the atmosphere, you "top out" and head downwind cross country to reach your next thermal to continue your flight.