Final answer:
During explosive volcanic eruptions, the ash cloud that forms can cause a decrease in the insolation reaching Earth's surface.
Step-by-step explanation:
During explosive volcanic eruptions, large amounts of ash can enter Earth's atmosphere and rise to an altitude of 20 kilometers.
The most likely effect of this ash cloud is a decrease in the insolation reaching Earth's surface.
Ash particles in the atmosphere can block sunlight and reduce the amount of solar radiation that reaches the surface of the Earth.
This can cause a temporary cooling effect on the climate.