On 15 June 2017, huge cumulonimbus clouds formed over the German Alps during the early evening, leading to intense thunderstorms several hours later

Weather ◽  
2019 ◽  
Vol 74 (9) ◽  
Keyword(s):  
Early Evening ◽  
Cumulonimbus Clouds

Patterns of human exposure to early evening and outdoor biting mosquitoes and residual malaria transmission in Ethiopia

Acta Tropica ◽  
2021 ◽  
Vol 216 ◽  
pp. 105837
Author(s):  
Teshome Degefa ◽  
Andrew K. Githeko ◽  
Ming-Chieh Lee ◽  
Guiyun Yan ◽  
Delenasaw Yewhalaw
Keyword(s):  
Malaria Transmission ◽  
Human Exposure ◽  
Early Evening ◽  
Outdoor Biting ◽  
Residual Malaria Transmission

scholarly journals Effects of the midnight temperature maximum observed in the thermosphere–ionosphere over the northeast of Brazil

2017 ◽  
Vol 35 (4) ◽  
pp. 953-963 ◽  
Author(s):  
Cosme Alexandre O. B. Figueiredo ◽  
Ricardo A. Buriti ◽  
Igo Paulino ◽  
John W. Meriwether ◽  
Jonathan J. Makela ◽  
...  
Keyword(s):  
Relative Intensity ◽  
Lower Thermosphere ◽  
Meridional Wind ◽  
Peak Height ◽  
Neutral Wind ◽  
F Region ◽  
Early Evening ◽  
Neutral Temperature ◽  
Constant Height ◽  
Meridional Winds

Abstract. The midnight temperature maximum (MTM) has been observed in the lower thermosphere by two Fabry–Pérot interferometers (FPIs) at São João do Cariri (7.4° S, 36.5° W) and Cajazeiras (6.9° S, 38.6° W) during 2011, when the solar activity was moderate and the solar flux was between 90 and 155 SFU (1 SFU  =  10−22 W m−2 Hz−1). The MTM is studied in detail using measurements of neutral temperature, wind and airglow relative intensity of OI630.0 nm (referred to as OI6300), and ionospheric parameters, such as virtual height (h′F), the peak height of the F2 region (hmF2), and critical frequency of the F region (foF2), which were measured by a Digisonde instrument (DPS) at Eusébio (3.9° S, 38.4° W; geomagnetic coordinates 7.31° S, 32.40° E for 2011). The MTM peak was observed mostly along the year, except in May, June, and August. The amplitudes of the MTM varied from 64 ± 46 K in April up to 144 ± 48 K in October. The monthly temperature average showed a phase shift in the MTM peak around 0.25 h in September to 2.5 h in December before midnight. On the other hand, in February, March, and April the MTM peak occurred around midnight. International Reference Ionosphere 2012 (IRI-2012) model was compared to the neutral temperature observations and the IRI-2012 model failed in reproducing the MTM peaks. The zonal component of neutral wind flowed eastward the whole night; regardless of the month and the magnitude of the zonal wind, it was typically within the range of 50 to 150 m s−1 during the early evening. The meridional component of the neutral wind changed its direction over the months: from November to February, the meridional wind in the early evening flowed equatorward with a magnitude between 25 and 100 m s−1; in contrast, during the winter months, the meridional wind flowed to the pole within the range of 0 to −50 m s−1. Our results indicate that the reversal (changes in equator to poleward flow) or abatement of the meridional winds is an important factor in the MTM generation. From February to April and from September to December, the h′F and the hmF2 showed an increase around 18:00–20:00 LT within a range between 300 and 550 km and reached a minimal height of about 200–300 km close to midnight; then the layer rose again by about 40 km or, sometimes, remained at constant height. Furthermore, during the winter months, the h′F and hmF2 showed a different behavior; the signature of the pre-reversal enhancement did not appear as in other months and the heights did not exceed 260 and 350 km. Our observation indicated that the midnight collapse of the F region was a consequence of the MTM in the meridional wind that was reflected in the height of the F region. Lastly, the behavior of the OI6300 showed, from February to April and from September to December, an increase in intensity around midnight or 1 h before, which was associated with the MTM, whereas, from May to August, the relative intensity was more intense in the early evening and decayed during the night.

scholarly journals New results on equatorial thermospheric winds and temperatures from Ethiopia, Africa

2017 ◽  
Vol 35 (2) ◽  
pp. 333-344 ◽  
Author(s):  
Fasil Tesema ◽  
Rafael Mesquita ◽  
John Meriwether ◽  
Baylie Damtie ◽  
Melessew Nigussie ◽  
...  
Keyword(s):  
Local Time ◽  
Zonal Wind ◽  
Meridional Wind ◽  
Local Times ◽  
Maximum Speed ◽  
Wind Speeds ◽  
Early Evening ◽  
Meridional Winds ◽  
Thermospheric Winds ◽  
Wind Surge

Abstract. Measurements of equatorial thermospheric winds, temperatures, and 630 nm relative intensities were obtained using an imaging Fabry–Perot interferometer (FPI), which was recently deployed at Bahir Dar University in Ethiopia (11.6° N, 37.4° E, 3.7° N magnetic). The results obtained in this study cover 6 months (53 nights of useable data) between November 2015 and April 2016. The monthly-averaged values, which include local winter and equinox seasons, show the magnitude of the maximum monthly-averaged zonal wind is typically within the range of 70 to 90 ms−1 and is eastward between 19:00 and 21:00 LT. Compared to prior studies of the equatorial thermospheric wind for this local time period, the magnitude is considerably weaker as compared to the maximum zonal wind speed observed in the Peruvian sector but comparable to Brazilian FPI results. During the early evening, the meridional wind speeds are 30 to 50 ms−1 poleward during the winter months and 10 to 25 ms−1 equatorward in the equinox months. The direction of the poleward wind during the winter months is believed to be mainly caused by the existence of the interhemispheric wind flow from the summer to winter hemispheres. An equatorial wind surge is observed later in the evening and is shifted to later local times during the winter months and to earlier local times during the equinox months. Significant night-to-night variations are also observed in the maximum speed of both zonal and meridional winds. The temperature observations show the midnight temperature maximum (MTM) to be generally present between 00:30 and 02:00 LT. The amplitude of the MTM was  ∼  110 K in January 2016 with values smaller than this in the other months. The local time difference between the appearance of the MTM and a pre-midnight equatorial wind was generally 60 to 180 min. A meridional wind reversal was also observed after the appearance of the MTM (after 02:00 LT). Climatological models, HWM14 and MSIS-00, were compared to the observations and the HWM14 model generally predicted the zonal wind observations well with the exception of higher model values by 25 ms−1 in the winter months. The HWM14 model meridional wind showed generally good agreement with the observations. Finally, the MSIS-00 model overestimated the temperature by 50 to 75 K during the early evening hours of local winter months. Otherwise, the agreement was generally good, although, in line with prior studies, the model failed to reproduce the MTM peak for any of the 6 months compared with the FPI data.

scholarly journals Covid-19: Early evening curfews are not effective and may backfire

2021 ◽  
Author(s):  
Sotiris Vandoros ◽  
Alina Velias ◽  
Sotiris Georganas
Keyword(s):  
Natural Experiment ◽  
Relative Difference ◽  
Relative Increase ◽  
Percentage Points ◽  
Early Evening ◽  
Before And After ◽  
Clear Identification ◽  
Econometric Approach ◽  
The Impact ◽  
Indoor Spaces

Background: During the COVID-19 pandemic, some countries have introduced early evening curfews. Several studies try measure the effectiveness of such measures across different countries, but clear identification of effects is elusive. Objective: We examined the impact of an early evening curfew on mobility by studying a shift in curfews from 9pm to 6pm in Greece. Data and Methods: We took advantage of a natural experiment in Greece, where curfews shifted from 9pm to 6pm in one Region, but not in another. We followed a difference-in-difference econometric approach, where we compared trends in mobility in groceries and pharmacies as well as residential spaces before and after the introduction of the 6pm curfew, in the two regions. Results: The relative difference in the time spent in groceries and pharmacies between the two regions before and after the intervention, is statistically insignificant [coeff: -9.95; 95%CI -44.358 to 24.458]. The relative increase in time spent in groceries and pharmacies after the 6pm curfew was only 4.625 percentage points [coeff: 4.625; 95%CI 1.412 to 7.838]. Conclusions: We found that the 6pm instead of 9pm curfew in Athens led to a 4.63 percentage point relative increase in time spent at home and had no effect on time spent in groceries and pharmacies. Considering that this was a result of a 18.75% reduction in hours where people were allowed to leave home, it seems that the early evening curfew led to more crowding in indoor spaces; which may facilitate the spread of disease. Lockdowns and other measures are necessary to tackle Covid-19, but it is important to avoid substitution by activities that contribute further to spreading the virus. Interventions should therefore be based on a thorough analysis of human behaviour.

Early Evening Questing and Oviposition Activity by the Culex (Diptera: Culicidae) Vectors of West Nile Virus in Northeastern North America

2007 ◽  
Vol 44 (2) ◽  
pp. 211-214 ◽  
Author(s):  
Michael R. Reddy ◽  
Timothy J. Lepore ◽  
Richard J. Pollack ◽  
Anthony E. Kiszewski ◽  
Andrew Spielman ◽  
...  
Keyword(s):  
West Nile Virus ◽  
North America ◽  
West Nile ◽  
Northeastern North America ◽  
Early Evening

Cumulonimbus clouds

Weather ◽  
2018 ◽  
Vol 73 (5) ◽  
pp. 153-153
Keyword(s):  
Cumulonimbus Clouds

scholarly journals On the Structure of Some Cumulonimbus Clouds which Penetrated the High Tropical Troposphere

Tellus ◽  
1954 ◽  
Vol 6 (4) ◽  
pp. 351-366
Author(s):  
Joanne Starr Malkus ◽  
Claude Ronne
Keyword(s):  
Tropical Troposphere ◽  
Cumulonimbus Clouds

Clouds in Tropical Cyclones

2010 ◽  
Vol 138 (2) ◽  
pp. 293-344 ◽  
Author(s):  
Robert A. Houze
Keyword(s):  
Boundary Layer ◽  
Tropical Cyclones ◽  
Small Scale ◽  
Propagation Characteristics ◽  
Convective Clouds ◽  
Stratus Clouds ◽  
Stratiform Precipitation ◽  
Static Energy ◽  
Convective Cells ◽  
Cumulonimbus Clouds

Abstract Clouds within the inner regions of tropical cyclones are unlike those anywhere else in the atmosphere. Convective clouds contributing to cyclogenesis have rotational and deep intense updrafts but tend to have relatively weak downdrafts. Within the eyes of mature tropical cyclones, stratus clouds top a boundary layer capped by subsidence. An outward-sloping eyewall cloud is controlled by adjustment of the vortex toward gradient-wind balance, which is maintained by a slantwise current transporting boundary layer air upward in a nearly conditionally symmetric neutral state. This balance is intermittently upset by buoyancy arising from high-moist-static-energy air entering the base of the eyewall because of the radial influx of low-level air from the far environment, supergradient wind in the eyewall zone, and/or small-scale intense subvortices. The latter contain strong, erect updrafts. Graupel particles and large raindrops produced in the eyewall fall out relatively quickly while ice splinters left aloft surround the eyewall, and aggregates are advected radially outward and azimuthally up to 1.5 times around the cyclone before melting and falling as stratiform precipitation. Electrification of the eyewall cloud is controlled by its outward-sloping circulation. Outside the eyewall, a quasi-stationary principal rainband contains convective cells with overturning updrafts and two types of downdrafts, including a deep downdraft on the band’s inner edge. Transient secondary rainbands exhibit propagation characteristics of vortex Rossby waves. Rainbands can coalesce into a secondary eyewall separated from the primary eyewall by a moat that takes on the structure of an eye. Distant rainbands, outside the region dominated by vortex dynamics, consist of cumulonimbus clouds similar to non–tropical storm convection.

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