border arc

基本解釋

Known in the weather world as a circumhorizontal arc, this rare sight was caught on film on June 3 as it hung over northern Idaho near the Washington State border.
愛達荷州上空出現(xiàn)的彩虹看起來像是著了火，這種現(xiàn)象在氣象學里被稱作環(huán)地平弧。
Next, the center of the pie is erased by drawing a white circle, and another arc is drawn to provide a visual border between the interior circle and the peripheral pie slices.
接下來，將繪制一個白色圓形擦掉餅圖的中心，并且繪制另一條弧線來提供內部圓形與外圍餅圖分區(qū)之間的可視邊界。