Why does Venus have a dense atmosphere?

Answer 1

The short answer is, because it has been producing and trapping greenhouse gases (primarily CO2, carbon dioxide) for billions of years.

It is currently believed that Venus used to have an atmosphere a lot more like ours until about 4 billion years ago. Venus, like Earth, has sufficient gravity to keep most of its atmospheric gases from flying off into space. However, Venus is 25% closer to the sun than we are, which means that before it developed its thick and reflective atmosphere, it would've received on average about 1.5 times as much solar energy as we do.

And unlike Earth, it has a very weak magnetic field. (The reasons for this are largely unknown, but may have something to do with its very slow 'day', which lasts 243 Earth days, or 1.1 times longer than the Venusian year itself.) It also lacks the tectonic plates that Earth has, which allow our mantle to vent a good portion of its heat energy in a somewhat controlled manner.

Possibly as a result of all this, Venus has a mantle which is much thicker and hotter than ours. This makes the planet extremely volcanically active, spewing great clouds of carbon dioxide and other greenhouse gases into the air. Additionally, it is believed that the heat of the mantle builds up until (about once every 700,000 years or so) it bursts through the crust of the planet all at once - which would not only produce a glut of greenhouse gases, but would boil off any water vapor into the upper atmosphere, where it would eventually be lost into space.

As a result, Venus is the victim of the greenhouse effect gone wild. At an average of 92 times Earth's atmospheric pressure at the surface, and temperatures exceeding 860 °F (460 °C), it is far too hot and dense for water vapor (or oxygen) to remain anywhere near the Venusian surface, and possibly reverse the effects.

Answer 2

The atmosphere of Venus consists mainly of carbon dioxide, and a small amount of nitrogen. The thick cloud cover is composed of sulfur dioxide and sulfuric acid droplets. Because of the dense atmosphere, the surface temperature ranges from 750 to 930 degrees Fahrenheit (398 to 498 Celsius). The surface pressure is 90 times that of Earth. That's like being one kilometer (over half a mile) under the ocean.

Answer 3

Venus has a very thick atmosphere because it has lots of gases around it.

Answer 4

It is dense, but it is hot, especially at the surface.

Answer 5

it be twice as dense as earth ya hear?