Light and Air

Light and air always surround us, influencing our human experience. Their interaction influences everything we see, and how our bodies experience temperature - from warm to cool. In this article learn about the  properties of light and air, concepts that are both beautiful and vitally important to our stable climate.  

Our story begins with the sun, Earth’s primary source of heat via its light. The sun, which has no solid surface, is really a massive collection of gas - hydrogen and helium - that has been "burning" for more than 4.5 billion years. As light travels from the sun to the Earth - influencing our temperature -  it is both reflected and absorbed, influenced by factors such as the land surface, cloud cover and our atmosphere. 

Light rays travel from the sun in straight lines through the air. Light from the sun is absorbed, scattered, and reflected by:

  • Air molecules
  • Water vapor
  • Clouds
  • Dust
  • Pollutants
  • Forest fires
  • Volcanoes

Light has the properties of waves. Like ocean waves, light waves have crests and troughs. The distance between one crest and the next is called the wavelength. The main source for visible-light waves our eyes receive is the sun, and sunlight is broken down into three components: visible light, ultraviolet light, and infrared radiation (or infrared light). 

Visible light has many variations of wavelengths, which we see as colors. On one end of the spectrum is red light, with the longest wavelength. Blue or violet light has the shortest wavelength. White light is a combination of all colors in the color spectrum. 

Infrared light is a type of radiant energy that is invisible to human eyes but that we can feel as heat. All objects in the universe emit some level of infrared radiation, but two of the most obvious sources are the sun and fire.

As objects grow hotter, they radiate energy dominated by shorter wavelengths, changing color before our eyes. A flame on a blow torch shifts from reddish to bluish in color as it is adjusted to burn hotter. In the same way, the color of stars tells scientists about their temperature.

Our Sun produces more yellow light than any other color because its surface temperature is 5,500°C. If the Sun's surface were cooler—say 3,000°C—it would look reddish. If the Sun were hotter—say, 12,000°C—it would look blue.

Recently, researchers at MIT have used computer modeling to simulate how our Earth’s warming could change the colors of the ocean. This is because temperature, ocean currents and ocean acidity will impact the growth of different types of phytoplankton as well as how they absorb and reflect light. 

Air pollution is closely linked to climate change. Given that the main driver of climate change is fossil fuel combustion, which is also a major contributor to air pollution,  efforts to mitigate one can improve the other.

 When light hits something and bounces off of it, it reflects. We see objects only when light reflects off them. Some objects reflect light more than others. A shiny surface such as a mirror reflects light, while materials that are dull or dark absorb light, soaking it up. 

Moonlight  is sunlight reflected from the dark gray surface of the Moon.  On Earth, reflective bright white ice sends some of the sun's light back to space, cooling the Earth.

Source Notes: 

Nasa Science, Tour of the Electromagnetic Spectrum

Let’s Talk Science: Light and Its Properties

Science Daily, Massachusetts Institute of Technology “Climate-driven changes in phytoplankton communities will intensify the blue and green regions of the world's oceans”


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