Online Panoramic Jigsaw Puzzle of a Rainbow at the Canyon of Dettifoss Waterfall in Iceland

Waterfalls are often very good places to find rainbows if the light is right. The spray frrom the waterfall itself causes light to refract and reflect in the water droplets to cause a rainbow. Ideally the sun should be low in the sky for a rainbow to appear. Visiting a waterfall early in the morning or late in the afternoon is therefore often the best time if you want to enhance the experience with the sight of a rainbow.

Detifoss is the most powerfall waterfall in Europe measured by the volume of water pouring over the falls. The water powering this 100 metre wide waterfall comes from the North-Eastern part of Iceland. On average, an amazing 200 cubic metres of water from the Jökulsá á Fjöllum river cascades down a drop of 44 metres into the canyon every second. When the river is running particularly strong, this can increase to a flow of 500 cubic metres of water per second. According to Springfrog's reliable volume converter, that's a mind-numbing 113,510 imperial gallons or 500,000 litres.

To give you an idea of just how much that is, the global average water usage per person with a water connection is 43.4 cubic metres per year according to the International Food Policy Research Institute. One second's average flow of 200 cubic metres is therefore the equivalent of 4.6 years of an average person's water usage, and at the high flow of 500 cubic metres per second, just a single second's flow could provide enough water for one person for 11.52 years! Another way to think about it would be to figure out how many people the average flow could contantly provide water for. If we divide a person's average usage of 43.4 cubic metres per year by 31,536,000 which is the number of seconds in a year we'll get the average usage per person per second which works out to be 0.000001376204972 cubic metres. The flow of 200 cubic metres per second could therefore supply a constant water supply for (200 divided by 0.000001376204972) = 145,327,188 people, which is 454 times Iceland's population of 320,000 as at April 2012.

Just as impressive is the actual power of the waterfall. With the average flow of 200 cubic metres per second and the drop of 44 metres, the power of this waterfall can be calculated as 200x44x1000×10 = 88 joules per second, in other words 88 Megawatts. With all that energy, the temperature of the water around the base of the waterfall actually tends to be warmer than the water at the top!