Measuring linear polarization of light scattered by a cloud of particles can help to retrieve their physical properties. Here we start an extensive study of polarimetric measurements of sand grains that can be found on the surface and in the atmosphere of Earth. Different techniques of measurements are compared using the LaMP nephelometer and PROGRA2 on ground and in microgravity during parabolic flights. The techniques used on ground bias the measurements. When the grains are lifted by air draught, differentiation is produced in the size distribution and nature of floating particles. When the grains are carried along with air flow, some grains become oriented along the flow direction at air speeds greater than a few m/s, producing abnormal negative polarization. On the other hand, measurements conducted under microgravity permit retrieval of the bulk optical properties of lifted sand grains with size greater than tens of micron.

1) D. Daugeron (daugeronx@moniut.univ-bpclermont.fr) is with the Laboratoire de Météorologie Physique, Université Blaise Pascal, 24 avenue des Landais, F-63177 Aubière cedex, France.
2) J.-B. Renard (jbrenard@cnrs-orleans.fr), B. Gaubicher, and B. Couté are with the Laboratoire de Physique et Chimie de l’Environnement, 3A avenue de la recherche scientifique, F-45071 Orléans cedex 2, France.
3) E. Hadamcik (edith.hadamcik@aerov.jussieu.fr) is with the Service d’Aéronomie, BP3, F-91371 Verrières le Buisson cedex, France.
4) François Gensdarmes (francois.gensdarmes@irsn.fr) and Guillaume Basso (guillaume.basso@irsn.fr) are with the Institut de Radioprotection et de Sûreté Nucléaire, BP 68, F-91192 Gif-sur-Yvette, France.
5) Corinne Fournier is with the Laboratoire Traitement du Signal et Instrumentation, 18 rue du Professeur Benoît Lauras, F-42000 Saint-Etienne, France.