Publications by authors named "R Baalbaki"
Aircraft observations have revealed ubiquitous new particle formation in the tropical upper troposphere over the Amazon and the Atlantic and Pacific oceans. Although the vapours involved remain unknown, recent satellite observations have revealed surprisingly high night-time isoprene mixing ratios of up to 1 part per billion by volume (ppbv) in the tropical upper troposphere. Here, in experiments performed with the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber, we report new particle formation initiated by the reaction of hydroxyl radicals with isoprene at upper-tropospheric temperatures of -30 °C and -50 °C.
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- * The study found that particle formation rates due to ion-induced processes are stable across temperature changes, while neutral particle formation rates increase significantly when temperatures drop from +10 °C to -10 °C.
- * Despite higher ionization rates, the formation of charged clusters is unlikely to be enhanced in upper tropospheric conditions; instead, neutral nucleation is expected to dominate, with humidity having little effect unless extremely low.
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- Aerosols from gas-to-particle processes significantly contribute to urban smog and haze, particularly through the formation of ammonium nitrate, which can thrive in polluted city conditions.
- Urban areas face complex variations in temperature and gas concentrations, influencing how quickly aerosols can form and grow.
- Experimental results from CERN's CLOUD chamber reveal that rapid temperature fluctuations can enhance nanoparticle growth, highlighting the influence of inconsistent ammonia emissions in cities on aerosol dynamics.
The main nucleating vapor in the atmosphere is thought to be sulfuric acid (HSO), stabilized by ammonia (NH). However, in marine and polar regions, NH is generally low, and HSO is frequently found together with iodine oxoacids [HIO, i.e.
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- Agriculture plays a vital role in food production but also leads to environmental issues, particularly in Southern Finland where agricultural lands significantly contribute to aerosol particle formation.
- Comprehensive studies revealed that emissions from soil, like ammonia, combine with sulfuric acid and organic compounds from plants to create new aerosol particles, which are relevant for climate.
- Clustering events for particle formation occur frequently under specific conditions, highlighting how agricultural areas can effectively contribute to regional climate cooling, potentially offsetting some negative impacts of farming on climate change.