Top: distribution of the reduced chi-square values in the simulation. The solid vertical lines show the values from the observed data. Middle: the distribution of the Pearson correlation coefficients in the simulation. The limit for significant correlation is about 0.7. The solid vertical lines show the values from the observed data. Bottom: distributions of p-values in a simulation with 15 (red), 30 (purple), 50 (blue), and 80 (green) clouds. The dotted line shows the p-value 0.003.