What is the technical reason for deterioration in performance of a gas turbine when the ambient temperature rises?

Answer 1

As the surrounding/ambient temperature increases, the temp of air entering the air compressor increases which means that the it's specific volume of air increases. Since the work of compressor = delta pressure x specific volume of air, then as the specific volume of air increases the work input of compressor increases and this is a problem because the total out put power of the turbine = work of the turbine - work of the compressor, so as the work of compressor increases, the total out put work of the gas turbine decreases.

And that's why the efficiency of gas turbine is better in winter than in summer.

Answer 2

As the ambient temperature rises, the air entering the gas turbine becomes less dense, leading to a decrease in the mass flow rate through the engine. This reduction in mass flow rate can result in lower power output and efficiency, as the engine is not able to combust as much fuel as it would under cooler conditions.