For Prelims: Formation of Rainbow

For Mains: Formation of Rainbow and its linkage with Climate Change

Why in News?

Recent research has revealed that an increase in greenhouse gas emissions is expected to change the amount of cloud cover and liquid precipitation, increasing the average number of rainbow days worldwide each year.

  • Globally, the average number of rainbow days is projected to rise by 4.0–4.9% year by 2100.

What did the research reveal about rainbows?

Less Rainbow-Producing Areas:

  • About 21-34% of geographical regions will no longer have rainbow days.
  • Except for Central Africa, Madagascar, and central South America, regions that would receive fewer rainbow days are anticipated to have less total precipitation by 2100.
  • All forecasts call for fewer yearly cloudy days and more annual dry days.

Regions with More Rainbows

  • The number of rainbow days will rise by roughly 66-79% under higher emission scenarios.
  • The frequency of rainbow days will rise in several nations, including India.
  • Additionally, more rainbow days will likely occur in African nations like Mali, Niger, Chad, Sudan, and Ethiopia.
  • Most hotspots for rainbow gain are found at higher latitudes or very high elevations, such as the Tibetan Plateau, where warming is expected to result in less snow and more rain.
  • The total amount of precipitation will rise, but there will be more dry days per year in two rainbow gain hotspots, eastern Borneo and northern Japan.

In what ways are the rainbow and climate change related?

About: 

  • When water droplets refract sunlight, a rainbow forms in the sky, a common atmospheric optical phenomenon.
  • Some of the light is reflected when sunlight strikes a raindrop. The light that makes up the electromagnetic spectrum has a wide range of wavelengths, and each is reflected at a unique angle. A rainbow is created as a result of the spectrum being divided.
  • Rainbows can also be seen nearby, along with fog, sea spray, and waterfalls.
  • It is an optical illusion, with no specific location in the sky.
  • The refraction and reflection of light create rainbows.
  • A change influences the refraction and reflection phenomena in a wave's direction.
  • A refracted wave may appear to be "bent," as opposed to a reflected wave, which may seem to "bounce back" from a surface or other wavefront.
  • In order of their wavelengths from longest to shortest, the colors that make up a primary rainbow are red, orange, yellow, green, blue, indigo, and violet.

Climate Change Connection

  • The warming of the atmosphere caused by human activities like burning fossil fuels alters the patterns, amounts, and types of precipitation and cloud cover.
  • Climate change will alter the distribution of rainbow occurrence because of changes in moisture evaporation and convergence.
  • This modifies cloud cover and precipitation patterns.

Source: DTE