Biological ice nucleation initiates hailstone formation

Michaud, Alexander B.; Dore, John E.; Leslie, Deborah L.; Lyons, W. Berry; Sands, David C.; Priscu, John C.

doi:10.1002/2014jd022004

Cited by 36 publications

(35 citation statements)

References 57 publications

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“…Ice-nucleating organisms are found in rain (Michaud et al 2014;Hara et al 2016;Failor et al 2017). Some are especially effective at promoting freezing, for example, spores of certain rust fungi (specifically, asexual urediospores) capable of long distance atmospheric transport, nucleate ice at temperatures as warm as − 4 degrees centigrade (°C) .…”

Section: Ice Formationmentioning

confidence: 99%

Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

Sheil

2018

For. Ecosyst.

144

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Theory and evidence indicate that trees and other vegetation influence the atmospheric water-cycle in various ways. These influences are more important, more complex, and more poorly characterised than is widely realised. While there is little doubt that changes in tree cover will impact the water-cycle, the wider consequences remain difficult to predict as the underlying relationships and processes remain poorly characterised. Nonetheless, as forests are vulnerable to human activities, these linked aspects of the water-cycle are also at risk and the potential consequences of large scale forest loss are severe. Here, for non-specialist readers, I review our knowledge of the links between vegetation-cover and climate with a focus on forests and rain (precipitation). I highlight advances, uncertainties and research opportunities. There are significant shortcomings in our understanding of the atmospheric hydrological cycle and of its representation in climate models. A better understanding of the role of vegetation and tree-cover will reduce some of these shortcomings. I outline and illustrate various research themes where these advances may be found. These themes include the biology of evaporation, aerosols and atmospheric motion, as well as the processes that determine monsoons and diurnal precipitation cycles. A novel theory-the 'biotic pump'-suggests that evaporation and condensation can exert a major influence over atmospheric dynamics. This theory explains how high rainfall can be maintained within those continental land-masses that are sufficiently forested. Feedbacks within many of these processes can result in non-linear behaviours and the potential for dramatic changes as a result of forest loss (or gain): for example, switching from a wet to a dry local climate (or visa-versa). Much remains unknown and multiple research disciplines are needed to address this: forest scientists and other biologists have a major role to play. New ideas, methods and data offer opportunities to improve understanding. Expect surprises.

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Section: Ice Formationmentioning

confidence: 99%

Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

Sheil

2018

For. Ecosyst.

144

View full text Add to dashboard Cite

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“…The INP activity in Pantoea spp. has been described previously (Akila et al, 2018;Jimenez-Sanchez et al, 2018;Kozloff et al, 1983;Lindow, 1978;Michaud et al, 2014;Stephanie & Waturangi, 2011 based on an assumed condensed water content of 0.4 g/m 3 (Petters & Wright, 2015). The gray-shaded area shows the envelope of INP observations in precipitation from Petters and Wright (Petters & Wright, 2015).…”

Section: Inp Characteristics Of Precipitation Samplesmentioning

confidence: 99%

Characterization of Ice‐Nucleating Particles Over Northern India

et al. 2019

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The sources and concentrations of ice‐nucleating particles (INPs) over India are not well known. Here, INP concentrations in rainwater from Northern India and a dust sample from the Thar Desert are characterized. Rainwater INP concentrations ranged between 104 and 3 × 107 L−1 water, spanning temperatures between −4 and −28 °C. During the monsoon season, INP concentrations were low and approached those in remote marine air mass. During the winter season, INPs active between −4 to −10 °C were occasionally observed. An increase in INP activity sometimes occurred after the initial onset of rain. The onset freezing temperature of samples active at warmer temperatures was shifted to colder temperature after heat treatment, suggesting that the INP activity stemmed from biological influence. Plating was used to isolate and sequence INP active bacterial strains from some of the rainwater samples, specifically strains of close taxonomic affiliation with the ice nucleating genera Pantoea. The size‐resolved ice nucleation active site density for 200–600‐nm particles of Thar Desert Dust ranged between 107 and 109 m−2 at −20 °C, values similar to dusts from other regions of the world. The data reported herein may help constrain models that seek to predict the impact of INP on the properties of mixed‐phased clouds over the Indian subcontinent.

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“…Gibbons et al (2018) also used the same scheme by DeMott et al (2015) to simulate a tropical deep convection and noted that increasing IN concentration led to the formation of more small ice particles and reduced total surface precipitation accumulation. However, only a few studies investigated the relationship between IN and the properties of hailstones (e.g., Michaud et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

The Roles of Mineral Dust as Cloud Condensation Nuclei and Ice Nuclei During the Evolution of a Hail Storm

et al. 2019

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Aerosols play important roles in the evolution of deep convective systems like hailstorms. In this study, the heterogeneous ice nucleation schemes have been improved in the Weather Research and Forecasting model coupled with a spectral bin microphysics (WRF‐SBM), which considered aerosols acting as ice nuclei (IN). A hail storm occurred around Tianshan mountains, northwestern China, was simulated with updated WRF‐SBM, and the results have been compared with satellite observations. Further, four sensitive simulation tests were conducted with different cloud condensation nuclei (CCN) and IN concentrations to investigate their respective roles during the evolution of the hailstorm. The increase in CCN concentration resulted in larger cloud droplet concentration and cloud water content, as well as enhanced condensational growth, which released more latent heat and led to stronger updraft at lower levels. The increase in IN number almost did not affect warm processes but led to larger ice crystal concentration and enhanced Bergeron process. Larger CCN concentration led to larger supercooled liquid water content, which in turn contributed to the enhanced hail growth by more efficient drop‐ice collisions and led to larger size of hail particles, while larger IN number reduced the size of graupel and suppressed the growth of hailstones. An analysis of the mobility of hail indicated increased frequency of larger hail with stronger sedimentation induced by more CCN. A further three ensemble runs with random perturbations on initial temperature and humidity were performed for each aerosol scenario, and the results suggested the robustness of simulated CCN and IN effects.

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Biological ice nucleation initiates hailstone formation

Cited by 36 publications

References 57 publications

Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

Characterization of Ice‐Nucleating Particles Over Northern India

The Roles of Mineral Dust as Cloud Condensation Nuclei and Ice Nuclei During the Evolution of a Hail Storm

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