The Environment of Fast- and Slow-Moving Tropical Mesoscale Convective Cloud Lines

Abstract

Rawinsonde data from GATE are composited to examine the environmental similarities and differences between fast-moving (line speed VL > 7 m s?1) and slow-moving VL < 3 m s?1) mesoscale convective cloud lines. Thermodynamic structures for the two types of line are similar with respect to the mixed-layer values of ?e and convective available potential energy, but the fast-moving lines have a more pronounced minimum in ?e at ?700 mb. Kinematic structure shows that the vertical shows of the horizontal wind is normal to the leading edge of convention in the fast-moving convective lines but parallel to the leading edge of the slow-moving cloud lines. The results suggest that the type of line (fast versus slow) which forms may be affected by the initial environmental conditions.