Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Latitudinal dependence of low cloud amount on cosmic ray induced
  ionization   A significant correlation between the annual cosmic ray flux and the amount
of low clouds has recently been found for the past 20 years. However, of the
physical explanations suggested, none has been quantitatively verified in the
atmosphere by a combination of modelling and experiment. Here we study the
relation between the global distributions of the observed low cloud amount and
the calculated tropospheric ionization induced by cosmic rays. We find that the
time evolution of the low cloud amount can be decomposed into a long-term trend
and inter-annual variations, the latter depicting a clear 11-year cycle. We
also find that the relative inter-annual variability in low cloud amount
increases polewards and exhibits a highly significant one-to-one relation with
inter-annual variations in the ionization over the latitude range
20--55$^\circ$S and 10--70$^\circ$N. This latitudinal dependence gives strong
support for the hypothesis that the cosmic ray induced ionization modulates
cloud properties.

13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
6
The categories of this paper are: astro-ph
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom