This week, Xavier Yvon and Bruno Cot, head of the Sciences department of L’Express, explain to you what the stratosphere is, at the heart of the Chinese balloons affair.
Listen to this episode and subscribe to La Loupe on Apple Podcasts, Spotify, Deezer, Google Podcasts, Podcast Addict And Amazon Music.
The team: Xavier Yvon (presentation and writing), Jules Krot (editing and production).
Credits: France2, BFM Business, RMC, Europe1
Music and design: Emmanuel Herschon/Studio Torrent
Image credits: Anne-Laure Chapelain and L’Express
Logo: Anne-Laure Chapelain/Benjamin Chazal
How to listen to a podcast? Follow the leader.
Xavier Yvon: Hi Bruno! I see that you came with a photo of the Earth… Can you explain to us?
Bruno Cott: This is a photo of our planet seen from the ISS and taken by Thomas Pesquet. Look, astronauts often evoke the fragility of the Earth seen from space with this intense blue they say and this thin layer of atmosphere which surrounds it like a halo. From a distance, the ISS is between 400 and 450 km high, so it looks like the atmosphere is a thin layer. But in reality it extends from the ground and up to the frontier of space. But the atmosphere is not defined with precision, or if you prefer, it does not disappear suddenly but gradually: it is a layer of different gases, mainly nitrogen and oxygen (at more than 90 %) but also other gases with exotic names such as argon, neon, carbon dioxide or the famous ozone. All these gases remain confined in our vicinity under the effect of gravity. And, the higher you go in altitude, the more they escape into space. That is for the physical principle.
Now this atmosphere is divided into several layers between the troposphere which is located at ground level and the mesosphere which is roughly located above 50 kilometers altitude. And, in between, there is….
Xavier Yvon: The stratosphere…
For further
Spy balloons: “This episode shows that China does not master technology to the end”
Is the Chinese balloon flying over the United States really a spy?