What is Tropical wave?
'''Tropical waves''', or '''easterly waves''', also known as '''African easterly waves''' in the [[Atlantic Ocean]], are a type of [[atmosphere|atmospheric]] [[trough]], an extended area of moderately low air pressure, leaning north to south, which move from east to west across the tropics creating areas of cloudiness and [[thunderstorm]]s. West-moving waves can also form from the tail end of frontal zones in the subtropics and tropics and may be called to as easterly waves, but these waves are not properly called tropical waves; they are a form of [[inverted trough]] sharing many characteristics with fully tropical waves. All tropical waves form in the easterly flow along the southern side of the [[subtropical ridge]] or belt of high pressure which is north and south of the [[Intertropical Convergence Zone]] (ITCZ). Tropical waves are normally carried westward by the prevailing easterly winds along the [[tropics]] and [[subtropics]] near the equator. They can lead to the formation of [[tropical cyclone]]s in the north [[Atlantic Ocean|Atlantic]] and northeast [[Pacific Ocean]]s. They can also lead to tropical storms which can also lead to hurricanes. ==Characteristics== A tropical wave is usually preceded by an area of sinking, intensely dry air, sloping as a northeast wind. With the passage of the trough line, the wind turns to the southeast, the humidity suddenly rises, and the atmosphere destabilizes, producing widespread showers and thunderstorms, sometimes severe. As the wave moves off westward, the showers slowly stop. 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. ==Atlantic== Tropica