Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Amateur Observers Witness the Return of Venus' Cloud Discontinuity   Firstly identified in images from JAXA's orbiter Akatsuki, the cloud
discontinuity of Venus is a planetary-scale phenomenon known to be recurrent
since, at least, the 1980s. Interpreted as a new type of Kelvin wave, this
disruption is associated to dramatic changes in the clouds' opacity and
distribution of aerosols, and it may constitute a critical piece for our
understanding of the thermal balance and atmospheric circulation of Venus.
Here, we report its reappearance on the dayside middle clouds four years after
its last detection with Akatsuki/IR1, and for the first time, we characterize
its main properties using exclusively near-infrared images from amateur
observations. In agreement with previous reports, the discontinuity exhibited
temporal variations in its zonal speed, orientation, length, and its effect
over the clouds' albedo during the 2019/2020 eastern elongation. Finally, a
comparison with simultaneous observations by Akatsuki UVI and LIR confirmed
that the discontinuity is not visible on the upper clouds' albedo or thermal
emission, while zonal speeds are slower than winds at the clouds' top and
faster than at the middle clouds, evidencing that this Kelvin wave might be
transporting momentum up to upper clouds.

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The categories of this paper are: chao-dyn
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
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The categories of this paper are: bayes-an
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The categories of this paper are: alg-geom
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The categories of this paper are: chem-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-ex
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The categories of this paper are: cond-mat
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The categories of this paper are: stat
1
The categories of this paper are: cs
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The categories of this paper are: solv-int
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The categories of this paper are: q-alg
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The categories of this paper are: dg-ga
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The categories of this paper are: adap-org
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The categories of this paper are: supr-con