They exert both a cooling effect on the surface by reflecting sunlight back into space, and a warming effect by trapping heat emitted from the surface. Clouds are one of the greatest areas of scientific uncertainty with respect to how much they influence climate on a global scale. The term "cloud radiative forcing" refers to the effects clouds have on both sunlight and heat in the atmosphere. More precisely, cloud radiative forcing measures how much clouds modify the net radiation, at wavelengths ranging from 0.3 to 100 micrometers, of the earth system. The cloud radiative forcing quantity may be defined as the difference between the observed Earth Radiation Budget parameters and what would have been observed if there were no clouds, while all other parameters of the system remain the same.  The IMAA research activity in this field is mainly devoted to develop a cloud radiative forcing methodology for HIRS/3 and IASI sensors. In order to compute clear radiance a new cloud clearing method has been developed. The Kriging cloud clearing developed does not require any assumptions on cloud top pressure, temperature profile, in adjacent field of views. This method is based only on the measurements (data points) which have been detected as clear at the cloud detection step and on statistical optimal estimation techniques. The Kriging cloud clearing scheme exploits the physical/statistical characteristics of clear field and the synergy with AMSU unit and produces a cloud cleared field with well defined statistical properties and error structures. An important property of the Kriging cloud clearing scheme is its uniform unbiasedness. Unlike cloud clearing methods which rely on IASI/AMSU or HIRS/AMSU regression relation, the Kriging cloud clearing scheme obtains almost bias-free estimates and therefore greatly improves reliability of the final product.