How was the rainbow made and why does it form after it rains?
First, the definition: rainbow—Any one of a family of large, colored, circular (or nearly circular) arcs formed by light (usually sunlight) falling on a population of water drops such as provided by rain, cloud, fog, or spray. The apparent center of the arcs is normally the shadow of the observer’s head, so the rainbow is a personal phenomenon with each person seeing a slightly different bow. Although the rainbow can form a circle, when caused by rain the bottom part of the circle is usually cut off by the ground, leaving an arc, the extent of which depends upon the elevation of the light. The term rainbow is not applied to the small, nearly circular arcs seen around the sun and antisolar point in clouds. These are the corona and glory. Nor is the term applied to the large circular arcs formed by light falling on ice crystals. These are the halos. Rainbows are seen as related groups of arcs, such as the primary rainbow (with red on the outside, blue on the inside), the (larger) seconda
