A New Look at the Vertical Shear of the Geostrophic Wind. Part I Dense Wind

Document Type : Original Article

Author

Member of Iranian Society of Marine Science and Technology (ISMST)

Abstract

From one point of view; we can divide atmosphere into two mediums. Barotropic medium, that in this medium, density doesn’t change in horizontal direction and isobaric surfaces are parallel to each other in vertical direction. This medium can be motionless, but if in this medium, motion would be taken place, geostrophic wind doesn’t change with respect to height. On the other hand, the baroclinic medium has horizontal gradient of density, and causes various horizontal gradient of pressure with respect to height and implies various horizontal velocity at different levels of the atmosphere. Therefore; geostrophic wind varies with respect to height in this medium. The horizontal gradient of density not only would produce by horizontal gradient of temperature, but also by horizontal gradient of humidity or combination of both. If horizontal gradient of density would be by both horizontal gradient of temperature and horizontal gradient of humidity – as in natural air, not in dry air – in the case; we name vectorial difference of geostrophic wind with respect to height; dense wind. The purpose of this paper is introduction of three versions of dense wind in natural medium of air, not dry air. Basic axis of first version of dense wind is founded by density, second by virtual temperature and third one by thickness of atmospheric layer. Formulae related to each version is derived and every one of them, represents effects of one type of variation of geostrophic wind with respect to height. First version exhibits advection of light or dense air, second represents virtual temperature advection and third one demonstrates advection of thickness in atmospheric layer. Dense wind is powerful tool for consistency of wind field. Therefore, because air is not dry, the variation of the geostrophic wind with respect to height should be describe with better tool, namely dense wind.

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