equatorial front

equatorial front, zone near the Equator in which the trade winds of the two hemispheres meet. The designation (about 1933) of this zone as a front was inspired by the close resemblance of its wind and weather patterns to those found along fronts in middle latitudes. Typically, the passage of a front is accompanied by long lines of cumulonimbus clouds, a rapid wind shift, and a sharp drop in temperature, presumably representing the transition from the warmer trade winds of the summer hemisphere to the cooler trade winds of the winter hemisphere. Most modern tropical meteorologists reject the concept of equatorial fronts, noting that their behaviour is much different from that of fronts in middle latitudes. The name equatorial-trough disturbance is preferred. The observed cooling, occurring almost entirely within the disturbed zone, is attributed to evaporation of falling rain and the lack of direct sunlight rather than to the replacement of one air mass by another.