[ad_1]
The highest clouds in the Earth's atmosphere have generally been a rare and beautiful sight but scientists say that they are now becoming more visible because of human activities.
A new study found noctilucent clouds – the silvery blue (and sometimes reddish – orange) clouds that shine in the sky – we can see it more frequently because of the increase in the water vapor in the atmosphere.
Researchers say this phenomenon is "an indicator of climate change of human origin".
Noctilucent clouds form when water vapor freezes around tiny dust particles from meteors in the mid-atmosphere (mesosphere) – about 50 miles above the surface of the Earth [19659002] water vapor to form in the air.
As observations became more frequent in the twentieth century, scientists began to wonder whether the Climate change made noctilucent clouds more visible.
In the new study, researchers from the Institute of Atmospheric Physics at Kuhlungsborn, Germany, used satellite observations and computer models to simulate the effects of greenhouse gases on cloud formation Noctilucent over the past 150 years
The use of fossil fuels releases carbon dioxide, methane, and water vapor. Simulation results show that methane emissions have increased water vapor concentrations in the mesosphere by about 40% since the end of the 19th century, which has more than doubled the amount of ice that form in the mesosphere.
The researchers say that's because the water vapor in the mesosphere comes from two sources: the water vapor from the surface of the Earth that is transported upward, and metha ne, a gas that produces water vapor through chemical reactions in the average atmosphere.
They conclude that human activities are the main reason why noctilucent clouds are significantly more visible than 150 years ago.
Franz-Josef Lubken, an atmospheric scientist at the Leibniz Institute of Atmospheric Physics and lead author of the study, said: "We speculate that clouds have always been there, but the chance of seeing one was very, very poor in historical times. " usually visible at dawn and dusk, when the sun illuminates them under the horizon.
The simulations revealed the presence of noctilucent clouds dependent on mesospheric conditions as well as the solar cycle (the phases in the sun's magnetic field that lasts about 11 years) and can fluctuate from one year to l & # 39; other.
But throughout the period studied, clouds became much more visible.
According to Professor Lubken, people living in mid-high latitudes now have a good chance of seeing noctilucent clouds several times
These clouds would probably have been visible only once every few tens from the years to the 19th century, he added.
The study is published in Geophysical Research Letters.
Source link
