Ash, per unit volume, water weighs a lot more than air...
Both water and air are many orders of magnitude heavier than the object / phenomenon I'm referring to.
Unfortunately though, it's not as straightforward as that, the phenomenon I'm on about doesn't weigh a thing when it's standing still which is handy because generally speaking, it never stays still.
Making matters worse, it only ever has what's called a relativistic mass because it's not as if you can go down Sainsburys and get it weighed at their meat counter.
It's tasteless, it's formless, it's odourless, It's virtually weightless.
It can harm you, it can heal you, it can even make you more attractive but it can also kill you .........