When can you see it?

From:  "Sara Foster"

What time of day is the best time of day to view a rainbow?

TB answered the call for help with this: 

The fundamental process at work in a rainbow is refraction. The best time to see a rainbow is dependent of the area you are in and time of year but generally is usually best seen about mid day, 2pm to 5 pm works best.

Todd responded quickly with this: 

Just after a light rain in the afternoon when the sun is higher in the sky. After it rains there is moisture in the air and if the sun is shining the water droplets in the air act as prisms and a rainbow is visible. This moisture does not last long, thus rainbows only last 5-10 mins. So watch the sky after a light rain and try to catch a rainbow. Happy rainbow watching.

Xyleman concluded with this: 

The most dramatic rainbows appear early or late in the day, with a bright sun low in the sky shining into falling rain. The brighter the sun and the heavier the rainfall, the better the rainbow. Rainbows appear in the sky opposite the sun. So if the sun is high in the sky, there will be no rainbow.