Changes in starlight reflected by the planet as it orbits its star provide insight into the physical processes that drive the transport of heat from the hot day side to the cooler night side. This technique, called phase curve analysis, also reveals details of the planet’s atmosphere, including the presence of clouds, and possibly even hints of the cloud composition.
ESA's Characterising Exoplanet Satellite, Cheops, will use the phase curve method to study some of the brightest stars in the mission's list of targets.

More about Cheops