Circulation - Circulation The circulation in Venus's...

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Circulation The circulation in Venus's troposphere follows the so-called cyclostrophic approximation. [3] Its windspeeds are roughly determined by the balance of the pressure gradient and centrifugal forces in almost purely zonal flow . In contrast, the circulation in the Earth's atmosphere is governed by the geostrophic balance. [3] Venus's windspeeds can be directly measured only in the upper troposphere (tropopause), between 60–70 km, altitude, which corresponds to the upper cloud deck. [17] The cloud motion is usually observed in the ultraviolet part of the spectrum , where the contrast between clouds is the highest. [17] The linear wind speeds at this level are about 100 ± 10 m/s at lower than 50° latitude. They are retrograde in the sense that they blow in the direction of the retrograde rotation of the planet. [17] The winds quickly decrease towards the higher latitudes, eventually reaching zero at the poles. Such strong cloud-top winds cause a phenomenon known as the super-rotation of the atmosphere. [3] In other words, these high-speed winds circle the whole planet faster than the planet itself rotates. [16] The super-rotation on Venus is differential, which means that the equatorial troposphere super-rotates more slowly than the troposphere at the midlatitudes. [17]
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Circulation - Circulation The circulation in Venus's...

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