Clouds have strange shapes

On February 18, 2003, astronauts on the ISS International Space Station saw a beautiful sight: These are noctilucent clouds, or night clouds, which are long and thin. Beautiful blue pieces hovering around earth orbit.

Once a talk through NASA broadcast in January 2003, astronaut Don Pettit said: 'For the past several weeks, we have enjoyed the beautiful views of these clouds in the south. bridge. We also often see them when flying in the skies of Australia and South America . ' People on the earth can also see them shining brightly after the sun goes down, even though the view from space is still more beautiful. Pettit estimates their height can be up to 80-100 km.

Impressive image of a lens cloud.(Photo: CAND.com.vn)

Pettit, who has been watching the cloud for many years, is also a scientist at Los Alamos National Laboratory, saying: " Although the cloudy sky looks like it is in outer space, they are actually in floor between earth atmosphere, at an altitude of 50 to 85 km . This floor is not only very cold (-125 ^o C) but also very dry - 100 million times more dry than the air in the Sahara. However, noctilucent clouds are made up of tiny ice crystals, equivalent to the size of cigarette smoke molecules. The sunlight reflected from these crystals makes them distinctive green.

Why is the ice crystal formed in the midst of the dry atmosphere is a mystery of noctilucent clouds. The crystals in the cloud need two conditions to grow: water molecules and something that they cling to, such as dust. Water that gathers on dust to form water droplets or ice crystals is a process known as 'nuclear composition' and they occur in all normal clouds.

University of Colorado Professor Gary Thomas specializes in noctilucent clouds, saying: 'Noctilucent clouds are a relatively new phenomenon. They were first seen in 1885, two years after the occurrence of Krakatoa volcanic eruption in Indonesia, causing sky-high smoke pillars of up to 80 km. Volcanic ash can create amazing sunset images in the night sky and has become one of the most popular relaxation pleasures around the world. '

At that time, a witness named TW Blackhouse noticed something strange. He stood outside after sunset and on some nights, he saw thin green smoke emitting light like electricity in the sky: glowing clouds. Some scientists at the time believed that noctilucent clouds were strange manifestations of volcanic ash. Eventually the ashes remained and Krakatoa's vivid sunset faded.

But these clouds still exist! Not only that, they also spread out. A century ago, they were restricted to latitudes above 500, you had to go to places like England, Scandinavi and Russia to see them. In recent years, they have appeared in Southern Utah and Colorado in the United States.

Near-earth clouds can pick up dust from desert winds, but it's hard to pick up dust up to the middle level of the atmosphere. Krakatoa may be the cause of 1885, but cannot explain the phenomenon of today. That could only be due to cosmic dust. Every day the earth comes in contact with tons of meteorites - scrap of waste from comets and small planets. Most of them are suitable sizes for noctilucent clouds. One of the reasons for the spread of noctilucent clouds is that the earth is heating up.

Lens-shaped clouds are also known as lentils clouds because they look like lentils, often to the right of the wind direction, formed along the high mountains and the slopes of the mountainside. , especially when there is a stable stream of dry and moist air flying over the mountain. When it flies up and reaches a saturation point, it condenses into a cloud. It is shaped like a lens composed of layers of static waves or sometimes looks like a long pillow. In some cases, many long strips of lentils are formed as a wave of clouds.

The lentil cloud has a unique point of not moving for hours, no matter how strong the wind is . The reason is because the air is caused by mountains or because the static waves at the top will be cold and spread out. This air flow continuously up and down in the cloud. Engine aircraft are afraid of flying near lentil cloud because will be affected by the propeller. But the roller coaster loves to find it, because the static wave system also participates in vertical air activities and it is easy to see where the rising air comes from.

' Surfing ' in this way is very strong and smooth, helping the riders soar up the remarkable height and distance. The record of surfing the clouds using the current technology of lentil cloud is 3,000km (in distance) and 14,938m (in height). If the air flowed into an arc in the mountain, there would be a disk-shaped cloud upside down. Lentil clouds are often confused with unidentified flying objects (UFOs) because of their disc-like shape.

Thuy Han