Phys.org May 25, 2022 Researchers from the Southern Methodist University will discuss a method for using infrasound pulses from detonated munitions to probe atmospheric phenomena at the 182nd Meeting of the Acoustical Society of America meeting. The sound they record propagates upward into the atmosphere and is refracted back down to the ground. The information they provide on the upper atmosphere can tell us about the winds aloft, and these can affect the weather at the ground. However, it requires sizeable source to have enough strength to reach the atmosphere and bounce back. Therefore, they set up detectors in the […]
Category Archives: Atmospheric science
How Long Do Black Carbon Particles Linger in the Atmosphere?
SciTech Daily January 1, 2022 In previous studies, the cloud nucleation values of black carbon were indirect measurements. An international team of researchers (UK, China) concurrently measured the concentration of cloud condensation nuclei and black carbon particles near heavily trafficked roads and industrial centers in Wuhan, China. They found that the activation diameter, or the size of the black carbon particle where half of the particles will nucleate and precipitate out, was 144 ± 21 nanometers at 0.2% supersaturation. How these black carbon–containing particles could act as cloud nuclei is determined by their size combined with their coatings, the authors say, […]
Researchers identify new meteorological phenomenon dubbed ‘atmospheric lakes’
Phys.org December 16, 2021 Researchers at the University of Miami will present a new meteorological phenomenon called “atmospheric lakes,” at the 2021 AGU meeting. Atmospheric lakes start as filaments of water vapor in the Indo-Pacific. They begin as water vapor streams that flow from the western side of the South Asian monsoon and pinch off to become their own measurable, isolated objects. They then float along ocean and coastal regions at the equatorial line in areas where the average wind speed is around zero. They researchers used five years of satellite data to spot 17 atmospheric lakes lasting longer than […]
Atmospheric metal layers appear with surprising regularity
Science Daily June 2, 2021 A team of researchers in the US (University of Colorado, UC Berkeley, Virginia Polytech, MIT) reported regular occurrence of mid-latitude thermosphere-ionosphere Na (TINa) layers over Boulder, Colorado. TINa layers occur regularly in various months and years, descending from ∼125 km after dusk and from ∼150 km before dawn. The downward-progression phase speeds are consistent with semidiurnal tidal phase speeds. One or more layers sometimes occur across local midnight. Elevated volume mixing ratios above the turning point of Na density slope suggest in situ production of the dawn/dusk layers via neutralization of converged Na+ layers. Vertical […]
The blast that shook the ionosphere
Science Daily March 17, 2021 An international team of researchers (India, Japan) reported an N-shaped pulse with period ~ 1.3 min propagating southward at ~ 0.8 km/s, as changes in ionospheric total electron content using continuous GNSS stations in Israel and Palestine, ~ 10 min after the August 4, 2020 chemical explosion in Beirut, Lebanon. The peak-to-peak amplitude of the disturbance reached ~ 2% of the background electrons, comparable to recently recorded volcanic explosions in the Japanese Islands. They succeeded in reproducing the observed disturbances assuming acoustic waves propagating upward and their interaction with geomagnetic fields…read more. Open Access TECHNICAL ARTICLE
Mysterious, Upside-Down Lightning May Not Be a Freak Phenomenon After All
Science Alert January 21, 2021 Lightning-like blue jets of atmospheric electric discharges fan into cones as they propagate from the top of thunderclouds into the stratosphere. They are thought to initiate in an electric breakdown between the positively charged upper region of a cloud and a layer of negative charge at the cloud boundary and in the air above. The breakdown forms a leader that transitions into streamers when propagating upwards. An international team of researchers (Denmark, Norway, Spain) report that they observed five intense, approximately 10-microsecond blue flashes from a thunderstorm cell. One flash initiated a pulsating blue jet […]
New tractor beam has potential to tame lightning
Phys.org November 11, 2020 Numerous experiments utilizing powerful pulsed lasers with peak-intensity above air photoionization and photo-dissociation have demonstrated excitation and confinement of plasma tracks in the wakes of laser field. An international team of researchers (Australia, USA – UCLA) developed and demonstrated an efficient approach for triggering, trapping, and guiding electrical discharges in air. It is based on the use of a low-power continuous-wave vortex beam that traps and transports light-absorbing particles in mid-air. They found a 30% decrease in discharge threshold mediated by optically trapped graphene microparticles with the use of a laser beam of a few hundred […]
Turbulence affects aerosols and cloud formation
Science Daily September 16, 2020 Traditionally the mechanics of cloud formation have not accounted for turbulence. Researchers at the Michigan Technological University investigated the aspects of cloud formation under controlled conditions including the effects of fluctuations, produced by turbulence. The measurements show a clear transition from a regime in which the mean saturation ratio dominates to one in which the fluctuations determine cloud properties. Measurements in the chamber show that turbulence can mimic the behaviors that have been attributed to particle variation, primarily size and composition. According to the researchers their model will help forecasters predict the fluctuations Planet Ocean-Cloud […]
Volcanic activity and changes in Earth’s mantle were key to rise of atmospheric oxygen
Science Daily June 9, 2020 A team of researchers in the US (University of Washington, Scripps Institution of Oceanography, University of Maryland, Arizona State University) combined data with evidence from ancient sedimentary rocks to show a tipping point sometime after 2.5 billion years ago, when oxygen produced by microbes overcame its loss to volcanic gases and began to accumulate in the atmosphere during the Great Oxidation Event. The data demonstrates that an evolution of the mantle of the Earth could control an evolution of the atmosphere of the Earth, and possibly an evolution of life as multicellular life needs a […]
Nanoparticles of Fungal Spores Have Been Detected Floating in Our Atmosphere
Science Alert January 26, 2020 Aerosol nanoparticles play an important role in the climate system by affecting cloud formation and properties, as well as in human health because of their deep reach into lungs and the circulatory system. The sudden appearance of large numbers of atmospheric nanoparticles is commonly attributed to secondary formation from gas-phase precursors. Researchers at UC Irvine have detected a mode of fungal fragments with a mobility diameter of roughly 30 nm released in episodic bursts in ambient air over an agricultural area in northern Oklahoma. These events reached concentrations orders of magnitude higher than other reports […]