A circumscribed halo is a type of halo, an optical phenomenon that circumscribes a related phenomenon, the 22° halo centred on the sun.
When observed, a circumscribed halo is normally oval in shape and, at the points directly below and above the sun, lies tangential to the 22° halo. It form when, as the sun rises, the upper tangent and lower tangent arcs extend into each other and close in on the 22° halo. As the sun rises above 70° it essentially covers the 22° halo.
A circumscribed halo is more intense in colour than the 22° halo. Like many other halos, it is reddish on the inner edge, facing the sun, and bluish on the outer edge.
Famous quotes containing the word halo:
“Most books belong to the house and street only, and in the fields their leaves feel very thin. They are bare and obvious, and have no halo nor haze about them. Nature lies far and fair behind them all. But this, as it proceeds from, so it addresses, what is deepest and most abiding in man. It belongs to the noontide of the day, the midsummer of the year, and after the snows have melted, and the waters evaporated in the spring, still its truth speaks freshly to our experience.”
—Henry David Thoreau (1817–1862)