  Temporal and spectral variations of black hole candidates during outbursts
have been reported in several publications. It is well known that during an
outburst, source becomes softer in first few days, and then returns to hard
states after a few weeks or months. In the present paper, we show variation of
Comptonization Efficiency (CE), defined to be the ratio of number of power-law
photons and number of soft photons injected to into the Compton cloud, as a
function of time in several outbursts. Since power-law photons are generated
through inverse-Comptonization of the intercepted soft photons, CE is a measure
of geometry of Compton cloud. Our investigation indicates that all outbursts
start with a large CE and becomes very small after a few days, when the Compton
cloud becomes small enough to intercept any significant number of soft photons.
CE returns back to a larger value at the end of outburst. We show co-variation
of count rates, frequency of quasi-periodic oscillations (QPOs), photon index
and CE and establish a general trend of disk geometry variation during
outbursts in all systems under consideration.a
