Behind a normal shockwave, what happens to the air's pressure and temperature?

• A. Both decrease
• B. Both increase
• C. Pressure increases while temperature decreases
• D. Pressure decreases while temperature increases

Answer: (B)

When flow passes through a normal shock, it is forced to decelerate from supersonic to subsonic in a very thin region, and the gas is compressed. That compression takes kinetic energy from the moving air and converts it into internal energy, so the air becomes more energetic. As a result, the static pressure rises and the static temperature increases behind the shock. It’s a rapid, irreversible change that also means the total (stagnation) pressure drops across the shock, even though the local pressure and temperature go up. So the best description is that both pressure and temperature rise behind a normal shock.