The Variability of Cloud Condensation Nuclei and Cloud Droplet Populations in Convective Clouds over the High Plains: How often are Continental Clouds Continental?
AbstractObservations and cloud microphysical modelling suggest that hygroscopic cloud seeding can be used to enhance precipitation from continental convective clouds. Model simulations demonstrate that the effect of such treatment varies with cloud microphysical characteristics. Significant enhancement is predicted for clouds with continental cloud droplet spectra, i.e. droplet concentrations on the order of 1000 cm^-3. The effect on maritime clouds with droplet concentrations of the order of a few 100’s cm^3 or less is predicted to be much smaller. A survey of past studies of aerosols is presented along with a newly-assembled collection of observations of convective cloud droplet concentrations over the High Plains of North America. It is shown that while a majority of clouds are indeed microphysically continental, a significant fraction of clouds in this region have microphysical characteristics that are maritime or intermediate between maritime and truly continental. Practitioners of hygroscopic seeding in this region need to monitor aerosol and cloud characteristics and target microphysically continental clouds if they want to optimize the effects of their seeding. Furthermore, indiscriminant hygroscopic seeding of clouds or an evaluation of results without regard to the maritime or continental character of the target and control clouds could lead to inconclusive and/or spurious results.
Authors that submit papers for publication agree to the Journal’s copyright and publication terms. Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the manuscript’s authorship and initial publication in Journal of Weather Modification. Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal’s published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in the Journal of Weather Modification. Authors are permitted to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process to encourage productive exchanges and greater citation of the published article.
Articles are published online using restricted access for the first year. After the first year, articles are made freely available online. Immediate open access for an article may be obtained by the author paying an open access fee which is in addition to the normal page changes. Authors are expected to honor a page charge in order to support publication and distribution of the journal. After the author approves the gallery formatted version for publication, the Weather Modification Association’s Secretary will invoice the corresponding author for the page charges and payment is due within 30 days.