Primary atmospheres are very thick compared to secondary atmospheres like the one found on Earth.

Planets such as Jupiter and Saturn have primary atmospheres.

Secondary atmospheres are relatively thin when compared to primary atmospheres like the one found on Jupiter.

The primary atmosphere was lost on the terrestrial planets due to a combination of surface temperature, mass of the atoms and escape velocity of the planet.

A primary atmosphere is an atmosphere of a planet that forms by accretion of gaseous matter from the accretion disc of the planet's sun.

A rare element is supposed to have been concentrated in the primordial or primary atmosphere of the earth that was largely lost during the early stages of the earth's history.

For better than a million years, it had been molten-hot, and it had lost most of its lighter elements in gaseous form along with its primary atmosphere, leaving little to form a lightrock crust.