Saharan Bishop ~ A huge Bishop ring envelopes the sun over Hungary. Monika Landy-Gyebnar captured the scene. All images ©Monika Landy-Gyebnar, shown with permission
At left the Saharan sand grains are tiny compared with those of builders' sand.
Atmospheric
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"In February a huge cloud of Sahara dust crossed the Mediterranean into Central Europe. It created "red" snow in the Italian Alps and muddy rain across Croatia, Slovenia, Hungary and Czech Rep. leaving ugly mud marks on cars.

Next day as the clouds parted a ~ 25 degree radius, spectacular Bishop's ring appeared around the Sun. In the evening the stars were very dim, Jupiter seemed to be not brighter than 0 magnitude (instead of -2), I could not see the Pleiades and the belt of Orion.

Usually the first dust arrives here in April and we might get some more events until early August, but it is rare to have such a dusty Saharan air mass reach Central Europe so out of season."
               

The Bishop ring is characteristically bluish near the sun with a pastel red edge.

It is a form of aureole or corona produced when tiny particles or droplets diffract sunlight.

Sulfate particles/droplets in the stratosphere from volcanoes are favourite sources but - as here - small tropospheric particles suffice.