The next question to answer is, how much the internal temperature can change without increasing the risk of failure? The operating temperature of the “most critical” component will give a maximum ambient temperature, while the cumulative power dissipation for all relevant components, such as power transistors, microprocessors, amplifiers and communication interfaces, will provide a figure for the amount of power dissipated by the overall design. Power dissipated, in Watts, converts linearly to energy, in Joules/second, which is in turn exhibited as heat. During operation the temperature of the air around components will continue to rise until it reaches a level that will inhibit further heat from being removed. At this time replacing the heated air with ambient air via forced air cooling will become necessary and is where selecting the appropriate level of airflow comes in.