Atmosphere of Venus water and subsequent rise of the levels of other greenhouse gases. Despite the harsh conditions on the surface, the atmospheric pressure and temperature at about 50 km to 65 km above the surface of the planet is nearly the same as that of the Earth, making its upper atmosphere the most Earth-like area in the Solar System, even more so than the surface of Mars. Due to the similarity in pressure and temperature and the fact that breathable air (21% oxygen, 78% nitrogen) is a lifting gas on Venus in the same way that helium is a lifting gas on
Greenhouse and icehouse Earth producing more CO and heating up the Earth's atmosphere. Earth is more commonly placed in a greenhouse state throughout the epochs, and the Earth has been in this state for approximately 80% of the past 500 million years, which makes understanding the direct causes somewhat difficult. An "icehouse Earth" is the earth as it experiences an ice age. Unlike a greenhouse Earth, an icehouse Earth has ice sheets present, and these sheets wax and wane throughout times known as glacial periods and interglacial periods. During an icehouse Earth, greenhouse gases tend to be less abundant, and temperatures tend to be