Journalists revel in these heat domes, but I'm not sure who started using the name. People feel to better understand what a heat dome is. In fact there is nothing new in this phenomenon.
Meteorologists speak of ridges (which are the opposite of troughs) or high geopotential heights. These heights are estimated at the altitude of the 500 hPa (or mb) pressure level. The height of this pressure level varies to form ridges and troughs. They are moving eastward as described by Rossby waves system. But sometime the motion of these waves is blocked: The ridge can stands several days on the same area.
The frequency of this type of blocking and of the high ridges of hot air seem to increase with the climate crisis. Under the ridge, the air is sinking, compressed and heated, leading to severe drought with all consequences we know for people and nature.