Nature 278, 531 - 532 (05 April 1979); doi:10.1038/278531a0

Martian extratropical cyclones

GARRY E. HUNT^* & PHILIP B. JAMES^†

^*Laboratory For Planetary Atmospheres, Department of Physics and Astronomy, University College London, London WC1, UK
^†Department of Physics, University of Missouri, St Louis, Missouri 63121

VIKING Orbiter 1 has recently photographed two cloud formations in the northern hemisphere of Mars which closely resemble satellite pictures of terrestrial extratropical cyclones. The pictures, (Figs 1 and 2) were acquired during the summer season and are the first evidence that baroclinic waves, prevalent during other seasons, also occur in summer. Physical properties of these systems deduced from the vidicon images and from the IR thermal mapping experiment (IRTM) are discussed here.

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