Sea Science: UV light can’t be felt, but danger it poses is real

May 25, 2018 by Jordanna Sheermohamed

Sea Science: by Jordanna Sheermohamed

As a sun-loving species, we humans often crave outdoor time in order to enjoy nature’s elements. It’s not until overexposure occurs that many wonder if nature is playing nice, or even fair.

We are born with a predisposition for our physical traits, genetically donated to us by our parents. These characteristics, such as our eye, skin and hair color, are ancestrally programmed as a result of geographic location and environmental habitat. Therefore, when one spends time outside of their immediate region, additional tools are necessary to adapt to the new environmental factors. For riders of the mean ocean streets, every day is a date with the harshest of elements.

The tilt of the Earth.

Geographic location and season are primary factors in determining the intensity of the sun’s incoming solar radiation, also known as “insolation” (not to be confused with building insulation). Also, radiation comes in varying intensities. Visible light is a small section of the entire spectrum, with other popular categories such as X-ray, infrared, and microwave values being the most familiar to our everyday lives. Just above intensity of visible light is ultraviolet, which cannot be seen or felt, but absolutely affects our body. Just below the intensity of visible light is infrared, which can also not be seen, but definitely is felt – the radiated heat of a toasty campfire or a hot clothing iron.

Imagine the sun as a giant flashlight, casting a beam of light upon our ball-like earth. The brightest light will be where the flashlight is directly aimed, with it gradually decreasing in intensity the further it is from the spotlight point. This is why the further you move away from the equator, generally, the weaker the sun’s insolation. Keep in mind that the earth does not move in a level orbit on its elliptical pattern around the sun; it also spins like a tilted top. When the northern hemisphere is tilted towards the sun (summer), the southern hemisphere is tilted away (winter), and vice versa. So the degree of insolation is highly dependent on location and time of year.

Protection can occur on several levels, as ideally it’s about the amount of layers between your skin (or eyes) and the sunlight. Obviously, being indoors provides nearly full protection. Being under a tree provides protection from above, but not on the sides. Clothing can be thought of as wearable protection. “Sunblock” or “sunscreen” is a liquid barrier conveniently applied for protection. Depending on the thickness of the product and the type of ingredients or particles it contains, it acts like a “liquid” thin layer of clothing.

Varying layers of protection may not fully prohibit sun exposure, but they can drastically reduce the absorption of radiation. Imagine cooking a chicken at 350 degrees versus 600 degrees; the former allows for even-heated cooking without burning the uppermost layer of skin, while the latter will burn the outside of the chicken before effectively cooking the inside.

Sunlight doesn’t come only from above, but also from the sides and below (remember the light of a flashlight travels away from its original source). Sunlight bouncing off a reflective surface such as water, sand, or snow merely redirects the insolation, and this must also be considered when it comes to sun safety. According to the Center for Disease Control, sand reflects roughly 20 percent to 30 percent of the sun’s UV rays, whereas snow or ice can reflect 80 percent to 90 percent of UV rays. The time of day also heavily influences the intensity of the sun’s ultraviolet rays. When the sun is directly above is when you get the strongest, most-focused light (again, think flashlight). This is why it’s best to increase protection between the hours of 10 a.m. and 2 p.m., when the sun is at its highest point in the sky.

Much like the barriers we put in place between ourselves and the sun’s light, clouds also help to diffuse some of that light. Cloudy days still produce sun exposure, but by incremental intensities compared with a cloudless sky. Still, no day can be considered entirely UV-free, and adequate preparation should always be considered.

Jordanna Sheermohamed is president and lead meteorologist of Weather Forecast Solutions, a weather-forecasting firm (  Comments are welcome below.


About Jordanna Sheermohamed

Jordanna Sheermohamed is president and lead meteorologist of Weather Forecast Solutions, a private weather-forecasting company ( Comments are welcome at

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