Tropical Wave (Cross)Relative Humidity/Vertical Motion
Vertical cross section of ageostrophic circulation/vertical motion (arrows) and the relative humidity (percent).
The strong upward vertical motion supports an upward surge of moisture between 15N 52W and 15N 49W, with the 70% contour extending just below the 500 hPa. The rapid decrease in relative humidity above 500 hPa is probably due to the area of upper convergence seen on the previous chart.
West of 15N 52W, note the area of downward vertical motion, resulting in adiabatic compression and drying of the atmosphere.