Is there a link between dust and thunderstorms?

Nature works in mysterious ways. Science helps unravel these enigmas over time to reveal all the surprising different associations causing the everyday weather you see. For this explainer, we can focus on the growing body of scientific research demonstrating through observation and modeling that the presence of dust in the atmosphere influences a developing thunderstorm! 

Dust is found locally or by being transported for days, if not weeks, at a time to cover vast distances on the global scale. Examples of dust sources may seem obvious at first to include top soils, open deserts, and sandy locations. Other potential sources are abandoned farm lands, unpaved parking lots, landfills, etc. Basically, any land use type with dust deposits that are susceptible to prevailing wind entrainment. Forces to loft dust include gusty and turbulent winds or by being mechanically stirred up by society via vehicular traffic and other industrial activities.

One vital link between dust and thunderstorms is how dust particles serve as both cloud condensation nuclei (CCN) and ice nuclei (IN). Essentially, dust particulates become “cloud seeds”. Dust can play an important role when water vapor is plentiful and thunderstorm updrafts are deep enough to allow sufficient vertical air mass cooling and condensation to occur. In other words, the phase conversion in open air for gaseous water vapor to liquid cloud droplets or to ice crystals is aided by available CCN/IN.

At first you might think more dust CCN/IN must mean more precipitation potential, but here's some context! Dust CCN are interesting as they have been shown to generate a greater number of longer-lasting small cloud droplets early during thunderstorm development. So, unable to start falling as rain the lighter, smaller cloud droplets and remaining dust particulates get carried higher in altitude by stronger updrafts (if present) to then become available as IN subsequent frozen precipitation generation (e.g., hail and graupel). 

The overall effect is actually less or delayed precipitation initially under a developing thunderstorm with an opportunity for more precipitation later in a storm’s life cycle should adequate environmental conditions (i.e., instability and moisture) continue to be present for thunderstorms to reach the mature cumulonimbus phase. Otherwise, if unable to precipitate back to the surface, condensation aloft facilitated by excessive dust CCN/IN would be carried out of the local region by prevailing winds and eventually evaporate back to a water vapor state. Therefore, rainfall spatial and temporal patterns, along with regional water vapor transport in general, are likely altered by how much dust CCN/IN is present, especially if thunderstorms or dust instigated clouds are able travel longer distances from their point of origin.

Photo Credit: Jonny William Malloy