Planetary lightning: Earth, Jupiter, and Venus (original) (raw)
Related papers
Lightning generation in planetary atmospheres
Icarus, 1983
The possibililies of lightning generation on other planets are considered, and the basic conditions that exist in terrestrial clouds during lightning discharges and the various theories of charge separation are reviewed. Recent measuremenls of cloud structure and whistlers, as well ,is oplical observation of lightning on Jupiter. suggest lhal charge separation and lightning discharges occur on other planets in ways similar to those in which lhe} occur on Earth. Using these terrestrial ideas, it is concluded that lightning on Venus will probably bc foumt in clouds that are located in regions of convection such as those observed downwind of the subso[ar point. It is also possible thal if volcanoes on Venus are erupting, the}' too can produce lightning discharges in their plumes althotlgh it seems unlikely lhal lhis process can account for the observed rate of discharge. Jovian lightning is most probably generated in the lower water-ice clouds. These clouds are of moderate temperatures and have strong convection and large mass loading, all important ingredients for electrical buildup, l,ightning is all bill ruled out for Mars. even though some electrilication ix possible owing to the large dusl Molms on that planel.
New results on planetary lightning
We present the latest observations from spacecraft and ground-based instruments in search for lightning activity in the atmospheres of planets in the solar system, and put them in context of previous research. Since the comprehensive book on planetary atmospheric electricity compiled by Leblanc et al. (2008), advances in remote sensing technology and telescopic optics enable detection of additional and new electromagnetic and optical emissions, respectively. Orbiting spacecraft such as Mars Express, Venus Express and Cassini yield new results, and we highlight the giant storm on Saturn of 2010/2011 that was probably the single most powerful thunderstorm ever observed in the solar system. We also describe theoretical models, laboratory spark experiments simulating conditions in planetary mixtures and map open issues.
Spectra of simulated lightning on Venus, Jupiter, and Titan
Icarus, 1985
Laser-induced plasmas in various gas mixtures were used to simulate lightning in other planetary atmospheres. This method of simulation has the advantage of producing short-duration, high-temperature plasmas free from electrode contamination. The laser-induced plasma discharges in air are shown to accurately simulate terrestrial lightning and can be expected to simulate lightning spectra in other planetary atmospheres. Spectra from 240 to 880 nm are presented for simulated lightning in the atmospheres of Venus, earth, Jupiter, and Titan. The spectra of lightning on the other giant planets are expected to be similar to that of Jupiter because the atmospheres of these planets are composed mainly of hydrogen and helium. The spectra of Venus and Titan show substantial amounts of radiation due to the presence of carbon atoms and ions and show CN Violet radiation. Although small amounts of CH4 and NH3 are present in the Jovian atmosphere, only emission from hydrogen and helium is observed. Most differences in the spectra can be understood in terms of the elemental ratios of the gas mixtures. Consequently, observations of the spectra of lightning on other planets should provide in situ estimates of the atmospheric and aerosol composition in the cloud layers in which lightning is occurring. In particular, the detection of inert gases such as helium should be possible and the relative abundance of these gases compared to major constituents might be determined.
Updated Review of Planetary Atmospheric Electricity
Space Science Reviews, 2008
This paper reviews the progress achieved in planetary atmospheric electricity, with focus on lightning observations by present operational spacecraft, aiming to fill the hiatus from the latest review published by Desch et al. (Rep. Prog. Phys. 65:955-997, 2002). The information is organized according to solid surface bodies (Earth, Venus, Mars and Titan) and gaseous planets (Jupiter, Saturn, Uranus and Neptune), and each section presents the latest results from space-based and ground-based observations as well as laboratory experiments. Finally, we review planned future space missions to Earth and other planets that will address some of the existing gaps in our knowledge. Keywords Lightning • Thunder • Radio emissions • Whistlers • Transient luminous events • Charging processes • SED-Saturn Electrostatic Discharges • Optical emissions • Dust • Dust devils • Triboelectric charging • Ionosphere • Spectrum • Cassini • Voyager • Mars Express • Venus Express • Remote sensing • Flash rate • Terrestrial gamma-ray flashes • Satellite • Mars • Venus • Jupiter • Titan • Saturn • Uranus • Neptune • Pioneer Venus Orbiter • Galileo • Electric field • Conductivity • Schumann resonance • Optical efficiency • Hydrocarbon • Cloud
Pioneer Venus Orbiter search for Venusian lightning
Journal of Geophysical Research, 1991
During 1988 and 1990, the star sensor aboard the Pioneer Venus orbiter (PVO) was used to search for optical pulses from lightning on the nightside of Venus. In our previous effort to use the star sensor for this purpose [Borucki eta!., 1981 ], we reported an upper limit to the lightning activity, but we were unable to show that lightning was being detected because the signal rate was indistinguishable from the false alarm rate. Because the periapsis altitude has increased by nearly a factor of ten since 1979, the star scanner views a much larger area of Venus than it did previously. This increased viewing area should provide an increased signal rate because the amplitude of optical pulses should still be above the detection threshold of the sensor if the flashes are as bright as terrestrial flashes. Because the false alarm rate did not increase, the increased viewing area allows a more sensitive search for lightning activity. Useful data were obtained for 53 orbits in 1988 and 55 orbits in 1990. During this period, approximately 83 s of search time plus 7749 s of control data were obtained. Our results again find no optical evidence for lightning activity. Within the region that was observed during 1988, the results imply that the upper bound to short-duration flashes is 4x 10 '7 flashes/km2/s for flashes that are at least 50% as bright as typical terrestrial lightning. During 1990, when the 2-Hz filter was used, the results imply an upper bound of 1 x 10 '7 flashes/km2/s for long-duration flashes at least 1.6% as bright as typical terrestrial lightning flashes or 33% as bright as the pulses observed by the Venera 9. The upper bounds to the flash rates for the 1988 and1990 searches are twice and one half the global teri'estrial rate, respectively. These two search•.covered the region from 60øN latitude to 30øS latitude, 250 ø to 350 ø longitude, and the region from •!i!•N latitude to 55øS latitude, 155 ø to 300 ø longitude. Both searches sampled mu•g of the nightside region from the dawn terminator to within 4 hours of the dusk terminator. These sear•'•s covered a much larger latitude range than any previous search. Our results show that the Beta and Phoebe Regio areas previously identified by Russell et al. [1988] as areas with high rates of lightning activity were not active during the two seasons of our observations. When we assume that our Upper bounds to the nightside flash rate are representative of the entire planet, the results imply that the global flash rate and energy dissipation rate derived by Krasnopol'sky [ 1983] from his observation Of a single storm are too high. ExPerimental measurements carried out to determine the amount of scattering occurring in the star scanner optics indicate that our previously determined upper bound to lightning activity is too low. The present results supplant the past results. The apparent conflict betWeen the radio data that indicate the presence of a large amount of lightning activity and' the optical data that indicate no lightning on the nightside, can be resolved bYnoting that theoretical considerations indicate lightning activity is to be expected only on the dayside. l. INTRODUCTION Although lightning in the terrestrial atmosphere has been studied for nearly two centuries, we still lack an understanding of the mechanisms that produce it [Williams, 1985]. Both the convective motion of atmospheric ions and the electrification of colliding precipitation have been advocated [Lhermitte and Williams, 1983].
Small lightning flashes from shallow electrical storms on Jupiter
Nature, 2020
Jovian lightning flashes were characterized by a number of missions that visited Jupiter over the past several decades. Imagery from the Voyager 1 and Galileo spacecraft led to a flash rate estimate of ~4×10-3 flashes/km 2 /yr on Jupiter. 1,2 The spatial extent of Voyager flashes was estimated to be ~30 km at half-width half-maximum intensity (HWHM), but the camera was unlikely to have detected the dim outer edges of the flashes given weak response to the brightest spectral line of Jovian lightning emission, the 656.3 nm H-alpha line of atomic hydrogen (known from lab experiments). 1,3-6 The spatial resolution of Galileo and New Horizons cameras allowed investigators to confirm twenty-two flashes with HWHM >42 km and estimate one between 37-45 km. 1,7,8,9 These flashes, with optical energies only comparable to terrestrial "superbolts" (2×10 8-1.6×10 10 Joules), have historically been interpreted as tracers of moist convection originating near the 5 bar level of Jupiter's atmosphere (assuming photon scattering from points beneath the clouds). 1-3,7,8,10-12 All previous optical observations of Jovian lightning have been limited by camera sensitivity, proximity to Jupiter, and long exposures (~680 ms to 85 s) hence some measurements were likely superimposed flashes reported as one. 1,2,7,9,10,13 Here we report optical observations of lightning flashes by Juno's Stellar Reference Unit 14 with energies of ~10 5-10 8 Joules, flash durations as short as 5.4 ms, and inter-flash separations of tens of milliseconds. The observations exposed Jovian flashes with typical terrestrial energies. The flash rate is ~6.1×10-2 flashes/km 2 /yr, more than an order of magnitude greater than hitherto seen. Several flashes are of such small spatial extent they must originate above the 2 bar level, where there is no liquid water. 15,16 Juno's Stellar Reference Unit (SRU) captured images of Jovian lightning on the dark side of Jupiter from a unique perspective of as close as 53,000 km above the 1 bar level (30 km/pixel resolution). The SRU is a broadband (450-1100 nm) imager designed to detect dim stars in support of spacecraft attitude determination. The camera's point spread function (PSF) spreads the optical signal of a point source over ~5 × 5 pixels, allowing unambiguous identification of small optical sources (see Extended Data Fig. 1). Fourteen lightning flashes (see Extended Data
Measurements of radio frequency signals from lightning in Jupiter's atmosphere
Journal of Geophysical Research, 1998
During the descent of the Galileo probe through Jupiter's atmosphere, the lightning and radio emissions detector (LRD) instrument measured r•dio frequency signals presumably from electrical discharges in the pl•net's atmosphere. The LRD was the only instrument that provided remote sensing, as well as in situ, measurements of atmospheric characteristics. The LRD measurements are presented here and some estimates a, re given on the energetics •nd frequency of occurrence of lightning in Jovian clouds. Propagation calculations of RF discharges in the Jovian atmosphere system and the statistics data obtained by the LRD, together with one very distinct lightning waveform, permit a unified •nd consistent interpretation of the data. We conclude that •t the time of probe entry, Jovian discharges occur with a rate about one hundredth that of the global yearly average on Earth (Ea. rth value is about 6 fia, shes km -2 yr -1) within about 15.000 km radius of the probe and that the average radiated power is of the order of 5 x 10 TM W. The change in the electric dipole moment in Jovian lightning is about 10 • coulomb m, roughly 100 times that of a typicM terrestria.1 discharge.
Spectral Irradiance Measurements of Simulated Lightning in Planetary Atmospheres
Icarus
Measurements of the spectral irradiance from approximately 380 to 820 nm are reported for laboratory simulations of lightning in the atmospheres of Venus, Jupiter, and Titan. The observations were made at 1 and 5 bars of pressure for Venus and Jupiter and at 1 bar for the Titan mixture. The spectra were obtained by observing laser-induced plasmas with a scanning spectrometer and an optical multichannel analyzer. Simulations of lightning show that atomic line and continuum radiation dominate the spectra. Weak molecular band radiation from CN was also observed for Venus and Titan. As the ambient pressure was increased from 1 to 5 bars, the prominence of the line radiation diminishes compared to the continuum radiation, some lines disappear, and the intensity of the molecular band radiation increases. Laboratory results for the venusian lightning spectrum are consistent with those found by the Venera 9 spectrometer when it viewed a storm on the nightside of Venus. For both Jupiter and ...
Lightning climatology of exoplanets and brown dwarfs guided by Solar system data
Monthly Notices of the Royal Astronomical Society, 2016
Clouds form on extrasolar planets and brown dwarfs where lightning could occur. Lightning is a tracer of atmospheric convection, cloud formation and ionization processes as known from the Solar system, and may be significant for the formation of prebiotic molecules. We study lightning climatology for the different atmospheric environments of Earth, Venus, Jupiter and Saturn. We present lightning distribution maps for Earth, Jupiter and Saturn, and flash densities for these planets and Venus, based on optical and/or radio measurements from the World Wide Lightning Location Network and Sferics Timing and Ranging Network radio networks, the Lightning Imaging Sensor/Optical Transient Detector satellite instruments, the Galileo, Cassini, New Horizons and Venus Express spacecraft. We also present flash densities calculated for several phases of two volcano eruptions, Eyjafjallajökull's (2010) and Mt Redoubt's (2009). We estimate lightning rates for sample, transiting and directly imaged extrasolar planets and brown dwarfs. Based on the large variety of exoplanets, six categories are suggested for which we use the lightning occurrence information from the Solar system. We examine lightning energy distributions for Earth, Jupiter and Saturn. We discuss how strong stellar activity may support lightning activity. We provide a lower limit of the total number of flashes that might occur on transiting planets during their full transit as input for future studies. We find that volcanically very active planets might show the largest lightning flash densities. When applying flash densities of the large Saturnian storm from 2010/11, we find that the exoplanet HD 189733b would produce high lightning occurrence even during its short transit.
Journal of Geophysical Research - Space Physics, 2014
Atmospheric electricity has been detected in all gaseous giants of our solar system and is therefore likely present also in extrasolar planets. Building upon measurements from Saturn and Jupiter, we investigate how the electromagnetic pulse emitted by a lightning stroke affects upper layers of a gaseous giant. This effect is probably significantly stronger than that on Earth. We find that electrically active storms may create a localized but long-lasting layer of enhanced ionization of up to 103 cm−3 free electrons below the ionosphere, thus extending the ionosphere downward. We also estimate that the electromagnetic pulse transports 107 J to 1010 J toward the ionosphere. There emissions of light of up to 108 J would create a transient luminous event analogous to a terrestrial “elve.”