An Extremely Elongated Cloud over Arsia Mons Volcano on Mars: I. Life Cycle. Hernández-Bernal et al. 2020. Manuscript accepted for publication on Journal of Geophysical Research This document is distributed under CC BY-SA 3.0 IGO license An Extremely Elongated Cloud over Arsia Mons Volcano on Mars: I. Life Cycle J. Hernández-Bernal1,2 , A. Sánchez-Lavega1 , T. del Río-Gaztelurrutia1 , E. Ravanis3 , A. Cardesín- 3,4 5 6 1 7 8 9 Moinelo , K. Connour , D. Tirsch , I. Ordóñez-Etxeberria , B. Gondet , S. Wood , D. Titov , N. M. Schneider5 , R. Hueso1 , R. Jaumann10 , E. Hauber6 1Dpto. Física Aplicada I, EIB, Universidad País Vasco UPV/EHU, Bilbao, Spain 2Aula EspaZio Gela, Escuela de Ingeniería de Bilbao, Universidad del País Vasco UPV/EHU, Bilbao, Spain 3European Space Agency, ESAC, Madrid, Spain 4Instituto de Astrofísica e Ciências do Espaço, Obs. Astronomico de Lisboa, Portugal 5Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, USA 6German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany. 7Institut d’Astrophysique Spatiale, CNRS/University Paris Sud, Orsay, France 8European Space Agency, ESOC, Darmstadt, Germany 9European Space Agency, ESTEC, Noordwijk, The Netherlands 10Freie Universitaet Berlin, Institute of Geological Sciences, Berlin, Germany Corresponding author: Jorge Hernández-Bernal (
[email protected]) Key Points: . We report a new phenomenon consisting of an extremely elongated water ice cloud (up to 1800 km) extending westward from the Arsia Mons volcano. The cloud reaches the mesosphere (45 km), and expands at a velocity of around 170 m/s in Martian Year 34. This cloud repeatedly forms in the early mornings, and repeats in a daily cycle between Ls 220º and 320º every martian year.