Here is why I I’ve long believed that life in the clouds of Venus is plausible. It's not just that the cloud environment is moderate in Temperature and Pressure (similar to Earth's surface) 1/8

And it’s not just that the clouds are a stable and long-lived liquid environment (unlike Earth's ephemeral clouds which are wispy and discontinuous, the cloud decks of Venus are permanent, deep, stable and global.) 2/8

And it's not just the ready availability of all the biogenic elements (CHOPNS and other trace elements including Cl, Mn and Fe), and the availability of both chemical and radiative energy sources to power possible life forms. (Plenty to eat!!) 3/8

It's also the emerging picture of Venus: likely past habitable liquid water oceans for billions of years on the surface: plenty of time to develop a robust, complex, varied and adaptable biosphere. When that surface dried out, where did the life go? Perhaps the clouds. 4/8

Also, we’re learning Venus, like Earth, has complex geochemical cycles involving interior, surface & atmosphere. Volcanoes likely feed gases into the air, which make clouds and are altered by sunlight, cycling back down to react with surface rocks, and round and round… 5/8

This complex chemical cycling creates a fertile environment for biological evolution. On Earth, life surfs along these "biogeochemical cycles". Venus has this same active character and thus may be able to support a biosphere. 6/8

It’s true that the clouds are composed extremely strong acid, but we keep discovering “acidophile” organisms on Earth and we simply don’t know the acid limit of life. 7/8

We really don't know and must keep exploring the entire solar system but IMHO life in the clouds Venus today is at least as plausible as life in the subsurface of Mars. I've been saying this for 23 years! 8/8

Here is the scientific case, more carefully laid out: http://funkyscience.net/wp-content/uploads/2016/11/AGU-Book_Grinspoon_Chapter.pdf