As air ascends it encounters lower pressure, expands and cools. (judithcurry.com)
In fact, Joanna Heigh of Imperial College in London, suggested that through dynamic coupling with the troposphere, via the Hadley circulation (in which moist air ascends in the tropic and descends as dry air at a latitude of about 30 °) the solar signal at the surface can be amplified. (sciencebits.com)
Both cloud types develop when clear air ascends, cooling adiabatically as it expands until either water begins to condense or deposition occurs. (britannica.com)