Many people call themselves “cloud watchers.” The people enjoy going outdoors, looking up at the sky and observing the clouds. Most cloud watchers knew the names of the different types of clouds, how they are formed, and what they can tell about the weather. This summer, cloud watchers are getting record-breaking glimpses of the rarest clouds in the sky. These rare blue clouds could be headed your way, and you don’t want to miss it.
Europe and the United States
These clouds have already been visible over the United States and Europe. This is strange because usually, these rippled blue clouds are only visible around the poles. They have already been visible this summer, and it is expected to continue. What makes these clouds even more amazing is that they have been seen at the lowest latitudes ever recorded.
These clouds are called noctilucent, or night-shining clouds. They are called this because they are only visible between dusk and dawn. Typically, these clouds form very high in the atmosphere. Usually, they form about 50-miles above the Earth’s surface, which is a region called the mesosphere. This is about four times higher than the cirrus clouds that we usually see.
These clouds are often only seen in the North and South pole during the summer because the temperature needs to be very cold for these clouds to form. During the summer in most parts of the world, the atmosphere just isn’t cold enough. They also form so high up in the air because the air is very thin in this part of the atmosphere.
How Are Noctilucent Clouds Formed?
The water in these clouds is transported up into the mesosphere from the lower atmosphere. They can also form when methane in the mesosphere breaks down when absorbed by the sun’s rays. They also need individual particles for the water to adhere to, such as dust, sand, or salt. In the mesosphere, these particles aren’t always available. At heights like this, the particles often come from meteors, which are lumps of space debris that burns up in the atmosphere, leaving behind dust. When the temperature is cold enough, the water in the mesosphere will condense in the dust, which forms clouds.
Night-shining clouds are usually so faint that we can only see them when the rest of the atmosphere is dark. When the sun is below the horizon, it shines up similar to a spotlight pointing up. This illuminates the highest parts of the atmosphere. The light from the sun shines on these clouds while passing though the ozone layer before it reaches your eyes. The clouds are blue because the ozone layer absorbs the red light, which allows only the blue light to pass through, which creates the night-shining cloud’s striking blue colors.
Night-shining clouds have a rippling appearance. This is due to atmospheric gravity waves. They are similar to waves in the ocean, but they travel through the air and not the water. The waves form when the wind blows over the mountains or during thunderstorms. This causes the ripple to move into the highest points of the atmosphere.
What Is Causing This?
Before now, the lowest altitude that we have seen these clouds was in 2002. Every year since, they have been moving south gradually. It wasn’t until June 2019 that the record was broken for the lowest point we have ever seen the clouds, and it occurred not far from Los Angeles. Experts believe that this is happening because the mesosphere is strangely wet, and contains more water than usual. This moisture is due to a substantial planetary wave that transported cold air and moisture into the North Pole.
Human Emissions Or Deep Solar Minimum
Many experts believe that human emissions could be the cause of this strange phenomenon. Over the years, we have been releasing more and more methane into the atmosphere. This causes more water modules to be produced in the mesosphere. Experts also believe that these clouds could be due to a deep solar minimum. This is a period of the sun’s 11-year cycle when it is the least active. During this period, the ultraviolet radiation from the sun is capable of destroying the water modules, allowing more of these clouds to form.
This first time these clouds were ever recorded was in 1883, right after the eruption of Krakatoa. When this happened, it spewed an enormous amount of dust into the atmosphere. Since this incident, we have been seeing the clouds more often, but not so low in the sky. The next time you are outside after dark, look up. You might be able to see the rarest clouds in the sky.