How many rainbows form each year?

The number of rainbows that form each year is not precisely measurable, as it depends on various factors such as weather conditions, geographical location, and the presence of sunlight and rain. In general, rainbows can appear whenever sunlight shines through raindrops, which can happen frequently in areas with regular rain showers and sunshine. Therefore, while it's difficult to quantify, millions of rainbows likely appear around the world each year.