Abstract from Berg, P., J. O. Haerter, P. Thejll, C. Piani, S. Hagemann, and J. H. Christensen (2009), Seasonal characteristics of the relationship between daily precipitation intensity and surface temperature, J. Geophys. Res., 114, D18102, doi:10.1029/2009JD012008.
“Past studies have argued that the intensity of extreme precipitation events should increase exponentially with temperature. This argument is based on the principle that the atmospheric moisture holding capacity increases according to the Clausius-Clapeyron equation and on the expectation that precipitation formation should follow accordingly. We test the latter assumption by investigating to what extent a relation with temperature can be observed intraseasonally in present-day climate. For this purpose, we use observed and simulated daily surface temperature and precipitation over Europe. In winter a general increase in precipitation intensity is indeed observed, while in summer we find a decrease in precipitation intensity with increasing temperature. We interpret these findings by making use of model results where we can distinguish separate precipitation types and investigate the moisture content in the atmosphere. In winter, the Clausius-Clapeyron relationship sets a limit to the increase in the large-scale precipitation with increasing temperature. Conversely, in summer the availability of moisture, and not the atmosphere’s capacity to hold this moisture, is the dominant factor at the daily timescale. For convective precipitation, we find a peak like structure which is similar for all subregions, independent of the mean temperature, contrary to large-scale precipitation which has a more monotonic dependence on temperature.”

The C-C does not seem to be a fits-all-sizes solution for off the hook suits. Indeed, one can point to devices like cloud chambers in nuclear physices where deviations from C-C are useful for diagnosis of incoming radiation. But those sytems are closely controlled, not like in nature.

Time and again I have argued that the abundance of uncharacterised or ill-quantified perturbations in natural climate systems make them sitting ducks for the models to be wrong. In the spectrum from the simplicity of Newton’s falling apple to the complexity of Navier-Stokes, they seem to converge towards the N-S end as a study becomes more detailed.

I’m still waiting for someone to explain how tropical cyclones can replenish and advance and rain for a thousand km or more over dry land, as has happened fairly often in West Australia.

This ‘super C-C’ scaling appears to arise from a super scaling of the upwards mass-moisture flux (i.e. for constant RH, SH rising by more than the C-C limit of 7%/degree), dominated by a super C-C scaling of the vertical velocity.

The situation is not so clear with longer durations and this is still an active area of meteorological research. In many cases C-C behaviour is not seen until durations get over about 6 – 12 hours and ARIs get down to 99%.

It is interesting to note that that the state-of-the-art in meteorological research with respect to short duration high intensity rainfall, high percentile rainfalls and PMFs etc is now way ahead of the state-of-the-art in climate modeling……

Any chance the pattern you show can be fitted into a climate model?