A volcanic eruption provides a natural experiment in which time constants for the onset and decay of the consequent radiative perturbation may be measured. The radiative and atmospheric responses also provide insight into how the top of atmosphere net balance of energy responds to perturbations. We analyse the response of the atmospheric humidity, temperature and radiative fields to the eruption of Mt Pinatubo to determine time constants for the growth and the decay of perturbations in these fields. We are able to distinguish between processes that respond directly to the insertion of aerosols into the atmosphere, and those, such as changes in the humidity and temperature, that involve slower dynamical processes and therefore have longer response times. The physical basis for these observations is discussed, and it is suggested that a valuable test of coupled climate models should be that they reproduce these response times, and the associated flux anomalies.