The fourth vial is not poured out on one of the elements of the Earth, but on the Sun. The Sun is the center of our solar system and of our inner fire, the I. People are scorched by the heat of the fire, but they do not change their inclination and blaspheme the Name of God.
The changing impact of the Sun
The pouring out of the fourth vial results in a changed effect of the Sun on us. Those who are carrying the sign of the beast experience the effect of the inner fire diffused by the Sun as the flames of hell which scorch and burn. These people tie themselves off from their divine origin, and are hardening themselves as a result of their hatred against God, according to Bock (p.250-278).

Schult (p.269-270) adds to this that the I is the spiritual sun of our being, just like the Sun is the center of the solar system. When the result of the outpouring of the vial is that the solar fire scorches man, this means that the luciferic I in man flares up. Man closes himself for God and uses the life, that God has given him, for himself. In this way, the Fall repeats itself.
Comparisons along the fourth ray in the spiral
A comparison of the impact of the fourth vial with the impact of the fourth trumpet shows that the trumpet results in the darkening of one third of the Sun. Here the influence of the trumpet resulted in the deadly cold effect on the feelings of the soul. The opening of the fourth seal resulted in the arrival of death. The horseman on the pale horse had the power to kill one fourth of the earth, which means to kill the physical body. So number four is connected in the case of the seal with physical death, in the case of the trumpet with the death of the soul, and in the case of the vial with the final disconnection of the self of its divine origin. We learn that those who persevere in the lower self will later experience that one’s soul dies, which is the second death, which finally results in the inability to use the physical resurrection body.