What cause a solar halo?

Answer 1

Halos are caused by Cirrus Clouds. Thin cirrus clouds plus bright sunlight almost guarantees you seeing something wonderful in the daytime sky.

Cirrus clouds are made of millions of hexagonal ice crystals 3 to 6 miles up in the Troposphere. Each crystal acting as a tiny prism refracting (bending) the sun's light and throwing it elsewhere into the sky.

Because the upper troposphere is almost always below freezing, ice crystals displays can be seen year-round.

But truly good displays in the United States are most common in the fall, winter, and spring when the northern jet stream descends southward, drawing down Arctic air masses whth

their treasure-trove

of jewel-like

icey

prisms.

The daytime sky abound with unexpected gifts, which can be yours for taking a moment to look up.

Answer 2

A solar halo is caused by sunlight being refracted, or bent, through ice crystals in cirrus clouds in the Earth's atmosphere. These hexagonal ice crystals act like prisms, bending the sunlight and creating a halo effect around the sun.