Tropical wave
A notable exception to the general characteristic of widespread precipitation behind a tropical wave occurs in the Atlantic.  Periodically, a surge of intensely dry air known as the Saharan Air Layer (SAL) is entrained behind a tropical wave, resulting in cloudless or nearly cloudless skies as convection is limited by the dry layer inversion. Also, any dust which may be present within the SAL reflects solar radiation, slightly cooling the atmosphere below it.