Earth & climate · the experiment
Measure the descent
Clouds more than 80 km up, a century of triangulations, and a climate model put to the test. Four questions, from beginner to expert.
1 · The trend2 · The rate3 · The 20th century4 · The method
1 · Read the verdict
Beginner
What has happened to the altitude of noctilucent clouds since the 1890 measurements?
2 · Compute today's descent
Since 1960, the LIMA/MIMAS model predicts a descent of 0.0233 km per year. The fit gives K = 0.52: the observed trend is K times the model's.
Intermediate
How fast are the clouds descending today, per century?
3 · Look back before 1960
Before 1960, the model descends by only 0.0036 km per year. Natural heights scatter between 79 and 85 km.
Expert
With K = 0.52, how much would the clouds have dropped between 1890 and 1960?
4 · Compare like with like
Expert
Why did the team refuse to compare recent lidar heights with old triangulations?
Descent measured
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