Introduction

2019 ◽  
pp. 1-6
Author(s):  
Paul Humphreys
Keyword(s):  
Dense Fog

During a summer break in college, I set out to solo hike the Pennine Way, a 267-mile footpath snaking across the moors of northern England. One day, my first goal was Stoodley Pike, a hill topped by a 121-foot stone folly. That morning, the Pike was covered in a dense fog, with visibility down to about ten yards. I lost the trail, and for about an hour, I had no idea where I was or whether I was hiking toward or away from the monument. I seemed destined to spend the rest of my holiday on the Pike, but suddenly the mist parted and right in front of me was the folly. When doing philosophy I am often reminded of that morning....

scholarly journals A Persistent Fog Event Involving Heavy Pollutants in Yancheng Area of Jiangsu Province

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Yuying Zhu ◽  
Chengying Zhu ◽  
Fan Zu ◽  
Hongbin Wang ◽  
Chengsong Yuan ◽  
...  
Keyword(s):  
General Circulation ◽  
Final Analysis ◽  
Analysis Data ◽  
Reanalysis Data ◽  
Thermal Factor ◽  
Atmospheric General Circulation ◽  
Long Duration ◽  
Low Visibility ◽  
Dense Fog ◽  
Good Visibility

In the early December 2013, dense fog involving heavy pollutants lasted for 9 days in the Yancheng area. The characteristics, formation, and lasting mechanisms of this persistent fog were analyzed based on observational data at the Sheyang site, reanalysis data, and final analysis data from NCEP/NCAR, combining with the weather background and meteorological and physical variable fields. Results include that (1) the fog process was characterized by long duration, low visibility, and high pollutants concentration, (2) the atmospheric general circulation contributed to the sustainability and development of the heavily polluted fog, (3) deep inversion was the key thermal factor causing the heavily polluted fog, (4) the fog exhibited obvious outbreaks with good visibility weather turned to severe fog several times, and (5) the weak cold air invasion and radiative cooling were the triggering factors to the sudden enhancement of the fog.

XXXIV

2008 ◽  
Author(s):  
Thomas Hardy
Keyword(s):  
Dense Fog ◽  
The Town

Next morning, accordingly, she rose at five o’clock, and went into the street. It was not yet light; a dense fog prevailed, and the town was as silent as it was dark, except that from the rectangular avenues which framed in the borough there...

Visibility of Laser Beams and Illuminated Delineator as a Function of Fog Density

1996 ◽  
Vol 1553 (1) ◽  
pp. 59-65
Author(s):  
Toru Hagiwara ◽  
Mamiko Yagi ◽  
Takuya Seo
Keyword(s):  
High Energy ◽  
Laser Beams ◽  
Specific Point ◽  
Dependent Variables ◽  
Road Geometry ◽  
Dense Fog ◽  
Normal Light ◽  
Few Data ◽  
Fog Density ◽  
Observation Room

In dense fog, adequate visibility of the delineator is important for providing the driver with road geometry cues. A new illuminated delineator that uses laser beams is proposed. Very few data have been published with regard to the visibility of laser beams in fog. However, laser beams can be expected to be highly visible in dense fog because of their high intensity, high energy, and directivity that is both monoclinic and strong. A study was conducted to evaluate the visibility of laser beams in fog. The effectiveness of two types of laser heads and an illuminated delineator containing two 10-W glow lamps was investigated in artificial fog. The dependent variables were luminance at a specific point on the laser beam and estimated brightness. The major independent variables were fog density and illuminance in the observation room. The laser beams were observed as sharp lines of light in dense fog. The visibility of the laser beams in fog had an inverse relationship to that of normal light. In addition, subjects reported that the directivity of the laser beams could effectively indicate the direction of the highway. However, the visibility of the laser beams was strongly affected by the illuminance in the observation room, and care must be taken to prevent drivers from looking directly at redundant laser beams. On the basis of these results, it is concluded that laser beams may be useful lighting sources in dense fog if this safety problem can be overcome.

A Computer Wind Model for Predicting Smoke Movement

1994 ◽  
Vol 18 (2) ◽  
pp. 60-64 ◽  
Author(s):  
Gary L. Achtemeier ◽  
James T. Paul
Keyword(s):  
United States ◽  
Wind Speed ◽  
Southeastern United States ◽  
Smoke Movement ◽  
Wind Model ◽  
Weather Event ◽  
Low Visibility ◽  
Dense Fog ◽  
Valley Flows ◽  
Insight Into

Abstract We are developing a numerical wind model to simulate airflow near the ground at night over terrain typical of the Piedmont of the southeastern United States. The purpose is to improve understanding of night winds and provide more accurate prediction of smoke movement when wind speed is low and wind direction is highly variable. These conditions often prevail when fog or a combination of smoke and fog produce low visibility. The model was tested with a weather event that produced local dense fog implicated as a factor in a highway accident. The model provides insight into drainage winds and valley flows and hence promises to be useful for predicting smoke movement at night. South. J. Appl. For. 18(2):60-64.

scholarly journals Experimental Study of Fog and Suspended Water Effects on the 5G Millimeter Wave Communication Channel

Electronics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 720 ◽  
Author(s):  
Ariel Etinger ◽  
Yosef Golovachev ◽  
Ofir Shoshanim ◽  
Gad A. Pinhasi ◽  
Yosef Pinhasi
Keyword(s):  
Millimeter Wave ◽  
Signal Propagation ◽  
Fifth Generation ◽  
Millimeter Wavelengths ◽  
Visibility Distance ◽  
Water Effects ◽  
Link Budget ◽  
Dense Fog ◽  
Theoretical Results ◽  
Good Agreement

Controlled experiments were conducted to examine the effect of fog on signal propagation in wireless communication and radar links operating in millimeter wavelengths. The experiments were carried out in a fog laboratory to verify theoretical results obtained from Liebe’s model. Attenuation and phase shifts of millimeter wave (mmW) radiation were measured, at different fog density characterized by the visibility distance and its water vapor content. Utilizing a vector network analyzer (VNA) enabled us to examine the actual atmospheric attenuation and the phase shift caused by the fog retardation. The experimental results demonstrate good agreement with the simulations even for very low visibility in highly dense fog. The study can be used to estimate link budget of mmW wireless links, including those allocated for the fifth generation (5G) of cellular networks.

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