However, the planet may be too hot to hold onto a thick hydrogen atmosphere (discussion). (solstation.com)
We suspect that water, the constituent of Saturn's deepest cloud deck, can suppress convection in the lighter hydrogen atmosphere for a period of decades, until finally buoyancy wins out and a large convective outburst ensues. (scientificamerican.com)
The lack of absorption features means that GJ 1214 b can not have a diffuse hydrogen atmosphere unless it also has a high cloud layer that blocks the starlight from streaming through. (scientificamerican.com)