METEOSAT water-vapor (5.7–7.1 μm) images are used to illustrate the formation of a low-latitude, upper-level vortex over NE Brazil in February 1979. Winds derived from cloud motions over three consecutive half-hourly METEOSAT infrared (10.5–12.5 μm) images show that the basic cause of the development is the disruption of an upper trough penetrating into low latitudes from the north. Cross-equatorial flow is set up and a cyclonic circulation appears in the southern hemisphere.

This content is only available as a PDF.