It would be better if there were some way to see atmospheric water while it is still vapour, before raindrops form.

But this cloud created by a U.S. Navy Super Hornet off the Peruvian coast is known as a 'shock collar' or 'vapour cone', created in certain atmospheric conditions at high speeds.

The idea is to test the effects on the atmospheric window of various pollutants, and also of water vapour, by releasing them into the building.