New studies have shown that the release of latent heat during cloud formation in rising air masses plays an important role in the formation of blocking high pressure areas ("blocking"). Current blocking theories do not take this process sufficiently into account. It could be a reason for the problems in the simulation of blocking in climate models and lead to future changes in the frequency of blocking high pressure areas in a warmer climate. In this project we want to improve our understanding of the relationship between latent heat release and blocking using Lagrangian diagnostics. This will be done using reanalysis data, global climate simulations and sensitivity experiments in which the release of latent heat is modified.