22-degree halo over St. Maarten: What appears to be a circular rainbow is actually the refraction (or splitting of light) and the reflection (or glints) of light through the ice crystals in cirrus clouds drifting 20,000 feet or more above overhead. It is called the 22-degree halo because the ring has a radius of 22 degrees around the sun (or the moon when seen at night). This halo appeared over the weekend and continued into this week. If the atmospheric conditions remain the same, the halo will be seen for a few more days.
Source: The Daily Herald https://www.thedailyherald.sx/islands/ring-around-the-sun