New Details on Venus’ Clouds from Venus Express

Mysterious clouds blanket Venus, obscuring our sister planet from view. These clouds billow up between 45 and 70 km above the surface, and in the upper part of the atmosphere, clouds swirl by at a rate of 300 km/h, driven by fierce winds. Composed mainly of sulfuric acid along with chlorine and fluorine, these clouds wouldn’t be friendly to life as we know it, but still, their mysteries beckon us. The science team from the European Space Agency’s Venus Express has been imaging the planet’s enigmatic atmosphere, and has released new images in several different wavelengths that provide new details on the clouds of Venus.

The Venus Monitoring Camera (VMC) on board Venus Express has been observing the top of the cloud layer in visible, near-infrared and ultraviolet wavelengths. Ultraviolet observations have shown a wealth of new details including a variety of markings created by different concentrations of different aerosols located at the top of the cloud layer.

The image above is a global view of the southern hemisphere of Venus, obtained from a distance of 30,000 km, with the south pole at the bottom and the equator at the top.

The appearance of the clouds changes dramatically from the equator to the pole. At low latitudes, the shapes are spotty and fragmented. Like water boiling in a pot, the clouds move because of convection, powered by the radiation of the sun heating the clouds and atmosphere. The brighter area visible on top of the darker cloud deck is made of freshly formed droplets of sulfuric acid.

At mid latitudes, the scene changes — convective patterns give way to more streaky clouds indicating that convection is weaker here, as the amount of sunlight absorbed by the atmosphere decreases.

At high latitudes, the cloud structure changes again. Here it appears as a dense, almost featureless haze forming a kind of polar cap or ‘hood’ on Venus. The dark, circular feature visible at the lower edge of the image is one of the dark streaks usually present in the polar region, indicating atmospheric parcels spiraling around and towards the pole.

Additional images provide close-up views of the structures described above and show details never seen before.

The second image zooms in on the equatorial region, showing details of the cloud top and of the bright areas made from sulfuric acid, from 20,000 km.

The third image is a close-up on the transition region between the equatorial regions dominated by convection and the mid-latitudes populated by streaky clouds. This region is located at about 40-50 degrees latitude and was imaged from a distance of about 15,000 km. The way the transition between structures and dynamics so different from each other occurs, is one of the outstanding enigmas in our understanding Venus.

Original News Source: Space Daily