Unraveling the mystery of how this phenomenon occurs in the upper layers of Earth’s atmosphere will help us understand the processes that determine weather conditions across the planet.
Scientists prepared special balloons with 7 cameras recording high-resolution images, measuring instruments, as well as LIDAR and memory banks of 32 terabytes on board. For 5 days they observed the upper layers of the atmosphere from a height of nearly 80 kilometers above the surface of the Earth, in the area between Scandinavia and Canada.
During the observations, the specialists took 6 million pictures and collected up to 120 terabytes of extremely valuable data. The main target of the observations were the famous and beautiful silver clouds. They appear in the mesosphere above the polar regions mainly in June and July. As they occur at altitudes of approx. 80 kilometers, they are also highly visible in Poland.
Atmospheric gravitational waves are not visible to our eyes, but thanks to silver clouds we can observe their formation and propagation in the atmosphere. Until now, we could only see them from the surface of the Earth or from airplanes, which is a two-dimensional view, but thanks to balloons and cameras, now scientists will be able to see a vertical cross-section of them and take a closer look in three dimensions.
Atmospheric gravitational waves carry energy from the lower atmosphere and create turbulence. NASA scientists have focused on the highest occurring ones, but the world of meteorology is also familiar with the more mundane ones.
NASA is investigating mysterious atmospheric gravitational waves occurring in Earth’s atmosphere. NASA photo.
They occur, for example, over oceans where there are usually no major obstacles and the atmosphere is stable, the air currents are then perfectly horizontal. However, when they pass over volcanic islands, of which there are many in the Pacific, they begin to deform. This happens when stratocumulus clouds, which are the most common cloud species on the planet, reach the hills.
This obstruction creates what is called an atmospheric gravity wave. Clouds hitting a mountain begin to rise on the windward side of the mountain and then fall again on the leeward side. This creates a wave that continues for hundreds or thousands of kilometers until the frequency of the waves decreases.
This can be compared to throwing a pebble into the calm water of a lake. Waves then appear that propagate radially from where the pebble hits the water surface. In the case of Earth’s atmosphere, where very strong winds blow, atmospheric gravity waves usually propagate in one direction, forming Stratocumulus clouds into something like an arrow. They are then called wave clouds. They can also form so-called cloud streets due to convection.
A better understanding of the role of these fascinating phenomena in shaping atmospheric conditions on our planet will help us make much more accurate weather forecasts.