Clouds from when water vapor oit of the air

Clouds form when water vapour condenses out of the air.

The air contains water vapour. When the air gets cold enough, the water vapour condenses into tiny droplets of liquid water.

They don’t fall because rising currents of air hold them up, and there are so many of them that we see them as clouds.

We call the conversion of a vapour into a liquid, condensation.

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.