Sunday, 19 April 2015
Have you ever wondered about the colors you see in these moments? What sunlight actually is? Yes, it's light from the Sun but so much more than that. Sunlight is both light and energy. Once it reaches Earth, we call this energy, "insolation," a fancy term for solar radiation. The amount of energy the Sun gives off changes over time in a never ending cycle. Solar flares (hotter) and sunspots (cooler) on the Sun's surface impact the amount of radiation headed to Earth. These periods of extra heat or extra cold (well, colder by Sun standards...) can last for weeks, sometimes months.
The beams that reach us and warm our skin are electromagnetic waves that bring with them heat and radiation, by-products of the nuclear fusion happening as hydrogen nuclei shift form to helium. Our bodies convert the ultraviolet rays to Vitamin D. Plants use the rays for photosynthesis, a process of converting carbon dioxide to sugar and using it to power their growth (and clean our atmosphere!) That process looks something like this: carbon dioxide + water + light energy -->glucose + oxygen = 6 CO2(g) + 6 H2O + photons → C6H12O6(aq) + 6 O2(g) Photosynthetic organisms convert about 100–115 thousand million metric tonnes of carbon to biomass each year, about six times more power than used my us hoomins.
We've yet to truly get a handle on the duality between light as waves and light as photons. Light fills not just our wee bit of the Universe but the cosmos as well, bathing it in the form of cosmic background radiation that is the signature of the Big Bang.
Once those electromagnetic waves leave the Sun headed for Earth, they reach us in a surprising eight minutes. We experience them as light mixed with the prism of beautiful colors. But what we see is actually a trick of the light. As rays of white sunlight travel through the atmosphere they collide with airborne particles and water droplets causing the rays to scatter. We see mostly the yellow, orange and red hues (the longer wavelengths) as the blues and greens (the shorter wavelengths) scatter more easily and get bounced out of the game rather early.