Because a cloud usually has a higher albedo than the surface beneath it, the cloud reflects more shortwave radiation back to space than the surface would in the absence of the cloud, thus leaving less solar energy available to heat the surface and atmosphere.
However, some heat from the Sun does get down to Earth. Clouds can trap that heat from the Sun. At night, when there’s no sunlight, clouds are still trapping heat. It’s sort of like clouds are wrapping Earth in a big, warm blanket. During the day, clouds can make the temperature on Earth cooler by blocking heat from the Sun.
How do clouds affect the Earth’s surface?
Clouds within a mile or so of Earth’s surface tend to cool more than they warm. These low, thicker clouds mostly reflect the Sun’s heat. This cools Earth’s surface. Clouds high up in the atmosphere have the opposite effect: They tend to warm Earth more than they cool. High, thin clouds trap some of the Sun’s heat.
But it’s a bit complicated: Clouds can both cool down and warm up the temperatures on Earth. Clouds can block light and heat from the Sun, making Earth’s temperature cooler. You’ve probably noticed this kind of cooldown on a cloudy day.
Do clouds block uv rays?
Clouds filter out some UV rays from reaching the ground. However, it depends on the type of cloud. Dark, water-filled clouds may block out more UV rays than high, thin clouds.
Clouds do not significantly block UV. Clouds are better at blocking visible light than UV rays, and unless there is complete cloud cover (no shadows), some harmful UV radiation is still getting through. Under heavy cloud cover, you may be protected from some UV, but partly cloudy conditions are suspected to aggravate UV rays through reflection.
Use Sunscreen Sunscreen is especially important when you’re golfing since you’ll be spending a lot of time outdoors. Seek Shade What’s a great way to give your skin a break from the sun’s rays?, and seek shade! Cover Up Besides sunscreen, other great forms of sun protection include covering up your body with clothing and hats. Use qsun, or 6 in addition are a couple more things to look into.
This of course begs the query “Can clouds or fog block or filter UV radiation?”
One source stated in general, clouds block UVB, but not UVA radiation. Dense clouds or fog can block most of the UVB in most instances. Of course, time of day, latitude, and altitude all have an effect on how much UVB gets through. This answer is not a substitute for professional medical advice.
Why does the Sun feel stronger on cloudy days?
The second theory is the idea of UV rays being redirected as they pass through thin wisp-like clouds. The combination of refraction and reflecting between varying clouds is resulting in a significantly greater UV strength at ground level. Complicating matters… On a cloudy day the sun doesn’t feel as hot as it does on a clear day.
Do greenhouses block UV rays?
While this issue of whether or not to block UV rays is contentious, it is true that certain greenhouse materials will block certain kinds of UV light. For example, greenhouse glass blocks 96% of UV-B radiation while only blocking 25-35% of UV-A. So, why is blocking UV light important? Should you get material with high UV-blocking capacity?