The impact of solar elevation angle on the upwelling radiation from tropical cyclone clouds

In earlier work we have demonstrated that TC clouds are, on average, net cooling in that they increase the upwelling radiation. This is due to a larger increase in daytime short wave reflectivity compared with the corresponding decrease in long wave emission that happens at night. While the trend computed over 20 years was for TC clouds to be cooling, there was approximately a 3:1 ratio between individual storms that were net cooling and net warming. In that earlier work, we noted that late-season storms tended to be preferentially warming. Here we demonstrate that this effect is dominated by local solar angle (which is highly correlated with seasonality) and over TC cloud extent.