Weather Modification—a Scenario for the Future

Abstract

The ever-increasing severe economic damage imposed on national and world wide economies by severe weather, the need for sufficient and safe water resources for an increasing world population, and the threat of adverse climate change led to this critical assessment of the state-of-the-art of weather modification (WM) and to a proposal of a road map for the future. Special attention is given to rain enhancement because it is further developed than snowpack augmentation, hail suppression, tornado and hurricane modification, and other weather-related disaster control ideas. The question of what makes a rain enhancement experiment acceptable to the scientific community is answered by the World Meteorological Organization's (WMO) criteria, which address statistical evaluation, the measurement of rain, the understanding of nature's precipitation processes with the underlying physics and dynamics of clouds and cloud systems, and the transferability of experiment design. These criteria are no longer specific enough or satisfactory and will have to be reconsidered. An actual WM experiment also involves a variety of techniques and technologies, aspects that need to be complemented by numerical modeling of clouds and cloud responses to seeding. Modeling also allows assessment of the extra-area effects, that is, detrimental effects of precipitation on adjacent areas. Assimilation models may be giving better estimates of the rain at the ground because they can integrate restricted information from radar and rain gauges with mesoscale meteorological and remote sensing, as well as hydrological, data. However, massive improvements in computer capacity are required to handle these problems. Weather modification has been progressing very slowly in the past because of the enormity of the problem and the fact that the precipitation process is far from being understood. Considering that rain increases are attempted within a range of 10%–20%, the lack of knowledge at corresponding accuracy is particularly evident in the fields of cloud physics, cloud and cloud systems dynamics, weather forecasting, numerical modeling, and measuring technology. Benefits of new intensive studies of precipitation processes will not be limited to WM; they are also vital to improving weather forecasting and climate change modeling. There is one additional aspect of WM; WM can also be used to test newly developed precipitation physics and models by studying if the clouds react to seeding in the predicted manner. This article is a wake-up call to put more intellectual and financial resources into the exploration and modification of the precipitation processes in all their forms. All these points lead to the suggestion of an outline of a national precipitation research and weather modification program.

Implementation of a Silver Iodide Cloud-Seeding Parameterization in WRF. Part I: Model Description and Idealized 2D Sensitivity Tests

“…To find out how this ratio changes with temperature, we performed extra experiments with surface temperature of 268 (T268) and 263 K (T263). A similar argument has been raised by many previous studies (Young 1996;Reisin et al 1996;Li and Pitter 1997;List 2004;Givati and Rosenfeld 2005). 15a-c.…”

Use of Biplane Grids for On-site Studies of Hurricanes

“…In these contexts, however, we must remain cautious that a perturbation of a complex organized flow field may also lead to instability and havoc. List (2004) says, "Interfering with tornadoes and hurricanes is hazardous, should it work, and is encumbered by possible legal challenges. It should await better scientific understanding."…”

If cannons cannot fight hail, what else?

“…In summary, for dealing with hailfall risks the use of cannons or explosive rockets is waste of money and effort. Seeding the clouds is a theoretically feasible method of hail suppression, but so far has not been supported by randomized experiments (LIST, 2004). Operational seeding evaluations, of which the reliability is dubious for various reasons (WMO, 1986), show uncertain results which vary by region.…”

“…The U.S. success was decidedly less than in Russia, and it was not clear whether this was due to local differences in hail formation processes or to delivery methods (SCHLEUSENER, 1968). Hail suppression by seeding is continued in the U.S.A., its results are still uncertain (KRAUS, 1999;LIST, 2004).…”