A bright display of noctilucent clouds, looking north from Burley‐in‐Wharfedale

Weather ◽  
2021 ◽  
Vol 76 (8) ◽  
Keyword(s):  
Noctilucent Clouds

A critical review of the paper ‘The earliest datable noctilucent cloud observation (Parma, Italy, AD 1840)’

The Holocene ◽  
2020 ◽  
Vol 30 (8) ◽  
pp. 1220-1221
Author(s):  
Peter Dalin
Keyword(s):  
Critical Review ◽  
Theory And Practice ◽  
Noctilucent Clouds ◽  
Noctilucent Cloud ◽  
The University

In the present critical review, my aim is to address serious calculation mistakes made by the authors. I do not want to review their interpretation of a given observation on 18 June 1840 made by Antonio Colla, who was a professor of Astronomy and Meteorology at the University of Parma. There is no sense interpreting Colla’s observation since the basic astronomical calculations have been made incorrectly by the authors Chiara Bertolin and Fernando Domínguez-Castro. Summarizing, in theory and practice, astronomer Antonio Colla could not have observed noctilucent clouds (NLC) at Parma on 18 June 1840. That is why the conclusions of the present paper are not valid.

First height comparison of noctilucent clouds and simultaneous PMSE

1993 ◽  
Vol 20 (24) ◽  
pp. 2845-2848 ◽  
Author(s):  
Urs Wälchli ◽  
Jacek Stegman ◽  
Georg Witt ◽  
John Y. N. Cho ◽  
Clark A. Miller ◽  
...  
Keyword(s):  
Noctilucent Clouds

Die Farbe leuchtender Nachtwolken

2021 ◽  
Author(s):  
Anna Lange ◽  
Christian von Savigny ◽  
Alexei Rozanov
Keyword(s):  
Noctilucent Clouds

<p>Das Phänomen leuchtender Nachtwolken (engl. Noctilucent clouds, NLCs) zeichnet sich durch die silbrig-blau oder hell-blau schimmernde Farbe aus. Unter der Verwendung des Strahlungstransfermodells SCIATRAN lassen sich unter der Annahme sphärischer NLC-Partikel die Spektren der durch NLCs gestreuten solaren Strahlung für einen bodengestützten Beobachter simulieren. Um die resultierenden Farben der NLCs möglichst objektiv bestimmen und darstellen zu können, werden die CIE (International Comission on Illumination) Farbanpassungsfunktionen und die CIE-Farbwerte verwendet. Die Darstellung erfolgt in sogenannten 2-D CIE-Farbtafeln, welches eine Standardmethode zur Visualisierung von Farbinformationen ist. Verschiedene Prozesse und Parameter, die die Farbe der NLCs beeinflussen können, wie unter anderem die Größe der NLC-Partikel, stratosphärisches Ozon und die Bedeutung von Einfach- und Mehrfachstreuung werden untersucht und diskutiert. Die Simulationen zeigen, dass die Größe der NLC-Partikel die Farbe der Wolken wesentlich beeinflusst und dass unrealistisch große Wolkenpartikel zu einer rötlichen Färbung führen. Darüber hinaus kann gezeigt werden, dass Ozon bei einer ausreichend großen optischen Tiefe der NLCs und bei bestimmten Beobachtungsgeometrien nur eine untergeordnete Rolle für die bläuliche Farbe der NLCs spielt. Des Weiteren zeigen die Berechnungen, dass der Beitrag der Mehrfachstreuung zur Gesamtstreuung nur von geringer Bedeutung ist, was eine zusätzliche Rechtfertigung für frühere Studien zu diesem Thema darstellt, die alle auf der Näherung der Einfachstreuung basieren.</p>

scholarly journals On microphysical processes of noctilucent clouds (NLC): observations and modeling of mean and width of the particle size-distribution

2010 ◽  
Vol 10 (2) ◽  
pp. 3605-3625
Author(s):  
G. Baumgarten ◽  
J. Fiedler ◽  
M. Rapp
Keyword(s):  
Particle Size ◽  
Linear Relationship ◽  
Size Distribution ◽  
Eddy Diffusion ◽  
Particle Sizes ◽  
Noctilucent Clouds ◽  
Atmospheric Variability ◽  
Distribution Width ◽  
Particle Properties ◽  
Microphysical Processes

Abstract. Noctilucent clouds (NLC) in the polar summer mesopause region have been observed in Norway (69° N, 16° E) between 1998 and 2009 by 3-color lidar technique. Assuming a mono-modal Gaussian size distribution we deduce mean and width of the particle sizes throughout the clouds. We observe a quasi linear relationship between distribution width and mean of the particle size at the top of the clouds and a deviation from this behavior for particle sizes larger than 40 nm, most often in the lower part of the layer. The vertically integrated particle properties show that 65% of the data follows the linear relationship with a slope of 0.42±0.02. For the vertically resolved particle properties (Δz=0.15 km) the slope is smaller and only 0.39±0.03. We compare our observations to microphysical modeling of noctilucent clouds and find that the distribution width depends on turbulence, the time that turbulence can act (cloud age), and the sampling volume/time (atmospheric variability). The model results nicely reproduce the measurements and show that the observed slope can be explained by eddy diffusion profiles as observed from rocket measurements.

scholarly journals First observations of noctilucent clouds by lidar at Svalbard

2003 ◽  
Vol 3 (1) ◽  
pp. 521-549 ◽  
Author(s):  
J. Höffner ◽  
C. Fricke-Begemann ◽  
F.-J. Lübken
Keyword(s):  
Lower Thermosphere ◽  
Degree Of Saturation ◽  
Noctilucent Clouds ◽  
Backscatter Coefficient ◽  
Maximum Volume ◽  
Height Range ◽  
Large Variability ◽  
The North ◽  
The Mean ◽  
Bad Weather

Abstract. In summer 2001 a potassium lidar was installed near Longyearbyen (78° N) on the north polar island of Spitsbergen which is part of the archipelago Svalbard. At the same place a series of meteorological rockets ("falling spheres", FS) were launched which gave temperatures from the lower thermosphere to the stratosphere. The potassium lidar is capable of detecting noctilucent clouds (NLCs) and of measuring temperatures in the lower thermosphere, both under daylight conditions. In this paper we give an overview on the NLC measurements (the first at this latitude) and compare the results with temperatures from meteorological rockets which have been published recently (Lübken and Müllemann, 2003).. NLCs were observed from 12 June (the first day of operation) until 12 August when a period of bad weather started. When the lidar was switched on again on 26 August, no NLC was observed. The mean occurrence frequency in the period 12 June–12 August ("lidar NLC period") is 77%. The mean of all individual NLC peak altitudes is 83.6 km (variability: 1.1 km). The mean peak NLC altitude does not show a significant variation with season. The average top and bottom altitude of the NLC layer is 85.1 and 82.5 km, respectively, with a variability of ~1.2 km. The mean of the maximum volume backscatter coefficient ßmax at our wavelength of 770 nm is 3.9×10−10/m/sr with a large variability of +/−3.8×10−10/m/sr. Comparison of NLC characteristics with measurements at ALOMAR (69° N) shows that the peak altitude and the maximum volume backscatter coefficient are similar at both locations but NLCs occur more frequently at higher latitudes. Simultaneous temperature and NLC measurements are available for 3 flights and show that the NLC layer occurs in the lower part of the height range with super-saturation. The NLC peak occurs over a large range of degree of saturation (S) whereas most models predict the peak at S=1. This demonstrates that steady-state considerations may not be applicable when relating individual NLC properties to background conditions. On the other hand, the mean variation of the NLC appearance with height and season is in agreement with the climatological variation of super-saturation derived from the FS temperature measurements.

scholarly journals Satellite observations of the quasi 5-day wave in noctilucent clouds and mesopause temperatures

2007 ◽  
Vol 34 (24) ◽  
Author(s):  
C. von Savigny ◽  
C. Robert ◽  
H. Bovensmann ◽  
J. P. Burrows ◽  
M. Schwartz
Keyword(s):  
Satellite Observations ◽  
Noctilucent Clouds

A comparison between ground-based observations of noctilucent clouds and Aura satellite data

2011 ◽  
Vol 73 (14-15) ◽  
pp. 2097-2109 ◽  
Author(s):  
P. Dalin ◽  
N. Pertsev ◽  
A. Dubietis ◽  
M. Zalcik ◽  
A. Zadorozhny ◽  
...  
Keyword(s):  
Satellite Data ◽  
Noctilucent Clouds
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