Compendium of Ceiling and Visibility
Articles for Operational Meteorology
Last update: 26 February 2002
AVIATION WEATHER CENTER LIBRARY
Articles in the compendia listed on this web site have been pulled from
numerous periodicals and textbooks resident at the Aviation Weather
Center library. These articles represent background knowledge and
continuing education for the forecasters to gain a better understanding
of the weather hazards encountered by aviators. The articles are listed
by the periodical, conference preprints, or texts, by year and title, and
contain a short synopsis of the contents. By listing the articles in this
manner they should be easy to find at your local library or university.
If you are visiting Kansas City and would like to use the library, please
set up an appointment.
MAIN MENU - Compendium of Ceiling and Visibility Articles
Ceiling and visibility are a major concern for air traffic decision makers. The
forecasting of these elements directly affects the safety and efficiency of the
National Air Space. A measured ceiling or visibility below certain values at St. Louis
Lambert Field may have significant impact on arrival rates, while the same values at
Dallas-Fort Worth or Boston's Logan Airport may have no impact at all. However, on a
daily basis in the United States, adverse weather that causes prolonged, major delays
at one major hub airport sooner or later will affect them all.
With this in mind, these ceiling and visibility articles are designed to give
practicing meteorologists or those with an interest in aviation weather a practical
background in these phenomenon. The articles date from 1950 to the present and contain
a variety of rules of thumb, definitions, and examples.
The ceiling and visibility
compendium is a follow-on to the turbulence and icing compendium released earlier this
year and represent only what is on file at the AWC Library.
Objective Forecasting Studies, May 1952
A 'how-to' from Eastern Air Lines on undertaking research studies for operational forecasts.
This is still valid today and gives the reader valuable insight in undertaking local studies.
The paper begins with an example of ceiling forecasts in Atlanta.
An Objective Aid to Local Forecasting, May 1952
Makes a case for the use of objective forecast aids. Suggests dividing the work on objectivity
into four classes and follows the progress of a study from beginning to completion.
Forecasting the Lake Breeze and Its Effects on Visibility at Chicago Midway Airport,
March 1954
A study of air pollution in the Chicago area and the problems with forecasting visibility with
its interaction with the lake breeze front. A suggested forecast procedure is offered which
includes variables such as clear sky, light winds and high pressure.
An Objective Method of Forecasting the Occurrence of Low Clouds in the McChord-Seattle
Area During the Summer Months, March 1955
A local Air Force study of cloud and fog advection in the Pacific Northwest primarily using
pressure difference as an indicator.
A Study of the Relationship Between Visibility and Temperature-Dewpoint Spread,
January 1958
A short paper on this subject which equates the difference between temperature and dewpoint
and the occurrence of low visibility and fog. Several nomograms are presented.
Mist - The Transition from Haze to Fog, June 1969
A study on the optical properties of haze and fog and how to determine which is obscuring
visibility.
Forecasting Local Weather by means of Model Output Statistics, October 1974
Explanation of how to use MOS as a predictor of several atmospheric variables including
ceiling and visibility. The paper has several exhibits explaining MOS results and skill.
FOG-82: A Cooperative Field Study of Radiation Fog, July 1982
Scientists from 10 universities and research laboratories combined to describe parameters
conducive to radiation fog formation. Research objectives include studies of fog mesoscale
meteorology, radiation studies, low-level water budget, vertical fog structure, fog
supersaturation, condensation nuclei, fog-water chemistry, and radiation fog life cycles.
Synoptic Frontal Analysis: Time for a Reassessment?, March 1991
Describes deficiencies in the Norwegian Model of frontal analysis and provides a resolution to
bridge the gap between the old and new methods of synoptic analysis.
Satellite Cloud Composite Climatologies: A New High-Resolution Tool in Atmospheric
Research and Forecasting, March 1992
GOES digital imagery has been collected and processed using new techniques over portions of
the United States since March 1988. High spatial and temporal resolution satellite cloud
composite climatologies (SCCC's) have been produced that represent cloud frequency maps for
each season. For each month studied, the cloud composite products represent the cloud
occurrence frequency for each GOES pixel location and depict the overall spatial distribution
of cloud cover over large portions of the United States
A Comparison of Ground and Satellite Observations of Cloud Cover, October 1993
An intercomparison of several systems including manual observations with satellite-derived
products. An attempt is made to distinguish thin from opaque clouds. Errors in observational
data are described with attempts to lessen them
Fog on the U.S West Coast: A Review, February 1994
Divides fog occurrences into four distinct phases and shows that periods of dense
fog at west coast NWS stations fall within a 5 to 15 day sequence of synoptic
events
Boston's East Wind, June 1954
An examination of the sea-breeze front and its associated weather at Logan Airport. Includes
some intrinsic characteristics of the front and its causes.
A Steam Fog at Galveston, Texas, October 1962
A short study on the causes and characteristics of dense fog formation on the Texas Gulf due
to cold air overrunning.
Forecasting Radiation Fog at Elkins, WV, May 1950
A study of the radiation fog at Elkins which includes the variables of gradient wind, surface
temperature, and dewpoint depression. The period of the study is from 1943 to 1949 and it
empirically finds that clear nights with easterly winds favor radiation fog at this location.
The Gulf Stream Front: A Cause of Stratus on the Lower Atlantic Coast, June 1950
This study attempts to help define the cause of stratus as a function of the Gulf Stream Front.
Evidence from sequences of weather charts and observations are presented as support to the
hypothesis of frontal interaction with this phenomenon.
On Forecasting Ceiling Lowering During Continuous Rain, July 1951
The author contends that ceiling heights may be predicted with sufficient accuracy by using a
set of empirically determined rules. He finds that during steady rain, the ceiling lowers in a
discontinuous fashion depending on several ambient factors such as frontal position,
near-ground turbulence, mixed intermittent heavy or light precipitation, and advection of cold
or warm air.
Monthly Percentage Frequency of Ceilings 2000 Feet or Higher over the United States,
September 1959
One of the first studies that links air traffic concerns involving delays or cancellations due
to ceiling. This study is a climatology that intends to help forecasters by providing some
advance guidance on the 2000 foot level. Maps of the percentage frequency of occurrence of
ceilings of 2000 feet or higher over the United States, excluding Alaska and Hawaii. A second
set of maps shows for each month the change in percentage from the preceding month.
Forecasting Middle Cloudiness and Precipitation Areas by Numerical Methods,
October 1959
A numerical prediction model suitable for computation using large-scale digital computers to
forecast amounts of middle cloudiness, areas of precipitation, and precipitation amounts is
presented. Along with the model is a nomogram for determining cloud categories such as partly
cloudy and clear using the 700 mb vertical velocity and dew point depression.
Heavy Fog Regions in the Conterminous United States, February 1969
Provides a geographic distribution of fog within the CONUS and shows that heavy fog
(visibility less than 1/4 mile) occurs more than 20 days a year at certain stations, of which
229 are air terminals. The distribution of fog is shown by conventional isopleth analysis and
by fog climate regions with characteristic frequency distributions.
Use of Model Output Statistics for Predicting Ceiling Height, December 1972
An examination of MOS and how to apply these statistics to ceiling forecasts. Several case
studies are presented from data obtained over three winter seasons at 95 eastern U.S. stations.
Prediction equations are developed for several levels and time periods.
Monthly Fog Frequency in the Continental United States, October 1973
Heavy fog (visibility <1/4 mile) statistics for 244 first order stations were used to
generate experimental objective analyses of the annual and monthly geographic distribution of
heavy fog. The resulting computer-generated map of annual distribution was compared with
existing analyses.
The Summertime Stratus over the Offshore Waters of California, October 1977
A study over one summer period using satellite imagery to explain the formation, movement, and
causative factors of summer stratus off the California coastline. The study discusses
upwelling and upper level synoptic air patterns and their interactions.
The Role of Inward Mixing in the Dissipation of Fog and Stratus, November 1978
A short article using satellite pictures offering a brief explanation for fog and stratus area
dissipation. The article mentions that fog and stratus will erode from the outer edges inward.
A Study of Visibility in Eighteen Cities in the Western and Southwestern United
States, November 1981
Airport visibility data for the period 1958 to 1979 are examined. The data are statistically
correlated to determine a threshold value below which the visibility is deemed poor. Several
conclusions are drawn from the results including an increase in the visibility as a result of
the 1971 Clear Air Act.
The Onshore Surge of Marine Air into the Pacific Northwest: A Coastal Region of Complex
Terrain, December 1986
A detailed case study of a typical Pacific Northwest event as well as a composite of several
events regarding marine surges and the strong winds, large temperature drops, and low ceilings
that often accompany them. The study shows that all major surges are initiated by synoptic
scale changes and that the mesoscale topography of the region amplifies the synoptic signal.
The Diurnal Variation of a Marine Stratocumulus Layer: A Model Sensitivity
Study, August 1989
A study detailing the influence of shortwave radiative heating during different
seasons on the decoupling of the cloud layer from the subcloud layer. Results for a
typical winter and summer are presented. The paper shows that decoupling can
strongly affect the surface energy balance
The Relationship of Marine Stratus Clouds to Wind and Temperature
Advection, November 1989
Compares observed cloud cover and satellite observations to model data during the
FIRE exercise. The study shows that there is a good correlation between wind
direction and temperature advection to marine stratocumulus coverage
An Expert System Approach for Prediction of Maritime Visibility
Obscuration, December 1989
Describes the AESOP system, an artificial intelligence approach to forecasting
maritime visibility obscurations. The paper describes the skill scores against
random chance and determines that this system can forecast fog events correctly 75
percent of the time
Diurnal Variation of Marine Stratocumulus over San Nicholas Island during July 1987,
June 1991
Explains how marine stratocumulus behaves over a water surface throughout the day which shows
that cloud thickness and liquid water content decrease during the day and increase at night
and provides statistical explanations for why this is. San Nicholas Island is 60 miles
southwest of Los Angeles, CA.
Marine Stratocumulus Cloud Clearing Episodes Observed during FIRE, April 1992
An examination including case studies of marine boundary layer and reverse flow off the
California coast which clears large areas of clouds. The study includes satellite pictures and
several exhibits to explain these clearing events
A Study of the Influence of Terrain on Fog Development, September 1993
A general purpose mesoscale numerical weather prediction model is used to simulate
the development of fog at Perth, Western Australia which shows that the uneven
local terrain and the development of local nocturnal winds may frequently determine
the location and timing of fog formation
Cloud Cover and Its Relationship to Relative Humidity during a Springtime Midlatitude
Cyclone, June 1994
An interesting study relating relative humidity as a single predictor of cloud cover and how
this predictor relates vertically. Some conclusions show that when the air is close to
saturation, current algorithms probably underestimate cloud coverage and that even small
changes in relative humidity can result in large changes in cloud cover
Numerical Forecasting of Radiation Fog. Part I: Numerical Model and
Sensitivity Tests, June 1994
Details a method to improve the forecasts of radiation fog events by using a
one-dimensional model of the nocturnal boundary layer forced by the mesoscale
fields provided by a 3D limited-area operational model
Numerical Forecasting of Radiation Fog. Part II: A Comparison of Model
Simulation with Several Observed Fog Events, June 1994
As in the first part of the study, only this part shows a correlation of observed
vs. model forecast radiation fog events. It shows that the model correctly
reproduced the time of fog formation and its vertical development when forcing
terms derived from observations were used
On the Forecasting of Winter Fog: A Geographic Approach, June 1963
Examines an empirical approach to fog forecasting using streamline analysis and suggests that
cool drier evening air represents more of a fog hazard than more saturated air. The study
suggests that streamline analysis produces higher skill scores than other methods of fog
forecasting.
Climatic Visibilities of the United States, June 1966
Climatological visibility data for fifty-three sites is used to evolve seasonal visibility
maps of the United States. The analysis is presented in the form of cumulative visibility
frequency distribution maps. A brief discussion of their use and limitations to describe
atmospheric opacity is included.
Ozone and Visibility Reduction in the Midwest: Evidence for Large-Scale Transport,
October 1977
Links ozone transportation over long distances to the incidences of photochemical smog over
the Midwest during a five day period in the Summer of 1975. This study correlates ozone to
haze with reduced visibility over a large region.
The Formation of Marine Fog and the Development of Fog-Stratus Systems along
the California Coast, October 1979
This study summarizes the results of seven field expeditions aboard the Naval Postgraduate
School's R/V Acania, designed to study the formation of marine fog along the California coast.
The research yields four different types of fog and stratus and gives triggering mechanisms
for each.
High Inversion Fog Episodes in Central California, August 1981
The meteorological conditions during a fog episode in central California during the winter are
described. Results show that these types of inversions are characterized by uniform weather
conditions with little variance. Several tables are shown.
Fog Forecasting for the Southern Region: A Conceptual Model
Approach, September 1997
A preliminary attempt at constructing a conceptual model is presented using input
from several parameters including cloud condensation nuclei, moisture availability
(saturation), and dynamic forcing. An illustration, and potential application, of
how the model could be used is detailed
9th Conference on Aerospace and Aeronautical Meteorology, June
Forecasting Upslope Stratus and Fog in the Central Plains
Outlines the synoptic patterns and situations associated with upslope fog and stratus and
contains two case studies from which a routine is developed.
Climatic Probabilities of the Vertical Distribution of Cloud Decks
A study from the Air Force Geophysical Laboratory detailing the use of models to
construct a ceiling climatology for Bedford, MA
An Application of Statistics to the Determination of Visibility and
Restrictions to Vision
A paper discussing a method of determining the weather or obstruction to vision and
of deriving the sensor equivalent visibility (SEV). Visibility sensors using the
measurement principles of forward scatter and backscatter are compares with each
other and with a transmissometer
Postprint Volume National Weather Service Aviation Workshop, March
The Effects of Weather on Delays in the National Airspace System
Outlines the causes of weather delays in the national airspace. The article outlines the
operations of the FAA ATCSCC, Center Weather Service Units, and others, in the decision making
process whose chief functions are to minimize air traffic delays and to maintain safety.
The Impact of Terminal Forecasts on Fuel Load Planning
This article discusses Delta Airlines' meteorology department and their requirements for
ceiling and visibility forecasts for fuel load planning.
Sea Fog and Stratus: A Major Aviation and Marine Hazard in the Northern Gulf of
Mexico
An examination of fog and stratus in this region. The purpose of this study is to develop
techniques to help the forecaster identify those synoptic patterns which are conducive to the
development of sea fog and stratus in the northern Gulf of Mexico. Several graphical aids are
offered.
The Effects of Summer Time Stratus at San Francisco International Airport on the
Nationwide Flow of Commercial Airline Traffic
A detailed examination of the role of low ceilings and visibilities at SFO and the effect on
nationwide air traffic decision making. Several graphics are offered. The roles of several
entities involved in the forecast process at SFO are detailed.
An Objective Forecasting Aid for Summertime Low Clouds During San Francisco
International Airport's Evening Rush
A detailed subset of the previous article during one time of the day at SFO. Several satellite
pictures are included as well as tables and graphs which will assist the forecaster to better
capture the low cloud heights during the evening in the summer.
13th Conference on Weather Analysis and Forecasting, August
Using the National Weather Service's NGM-Based Statistical Guidance for Short-Range
Forecasting
A study of the benefits and shortcomings of the NGM statistical model guidance. Establishes
many constructive guidelines for its use.
5th Conference on Aviation Weather Systems, August
MEMFOG - The Memphis Fog Algorithm
A document from Federal Express Meteorology studying an algorithm for the onset of
fog at the Memphis International Airport. Documents fog frequency by length of time
and time of night including the thresholds and limits of the study
Analysis of Rapidly Developing Fog at the Kennedy Space Center
An investigation of rapidly developing fog events that developed near the ‘go-no
go’ decision times for the shuttle landing. Describes efforts to forecast these
short-fuse events
10th International Conference on Interactive Information and Processing
Systems for Meteorology, Oceanography amd Hydrology, January
"Meteo-Fuzzy" - An Expert System for Fog Forecasting
A Romanian study describing the construction of an expert system to aid in
forecasting fog events using a mesonet dataset
6th Conference on Aviation Weather Systems, January
Use of NGM Regional Profile Forecasts for Fog Forecasting for Space Shuttle
Landing Operations at KSC
At study by the Spaceflight Meteorology Group at Johnson Space Center which details
the use of the NGM to predict fog occurrence at Kennedy Space Center in Florida in
order to provide the space shuttle the opportunity for a ‘go-around’ should fog be
impacting the landing site at KSC (CCP 1993-4 C/V)
The Accuracy of Ceiling and Visibility Forecasts Produced by the National
Weather Service
Verification results of local ceiling and visibility forecasts are presented for 90
stations within the contiguous United States. Verification scores are computed and
the results analyzed
Characterizing the Causes of Low Ceiling and Visibility at U.S. Airports
This study examines the exposure of U.S. airports that experience considerable delay (and are
responsible for significant up- and downstream delay at other airports) to low ceiling and
visibility conditions. Frequencies of occurrence of these events are tabulated and correlated
with IFR and IFR/VFR transitions as relevant measures of delay. The paper includes a decision
logic table for characterizing IFR events.
Short-Term High-Resolution Forecasting of Cloud Ceiling Heights and Visibilities
Discusses short-term forecasts for less than two hours when compared to model and persistence
forecasts. The paper shows that there is a need for more detailed and frequent weather
information from both observations and short-term numerical guidance.
A Hybrid Model for Predicting Fog and Stratus Clouds
A study by the U.S. Air Force and Saint Louis University describing a hybrid,
analytical/numerical, one-dimensional fog and stratus prediction model. It shows
examples of model outputs, and describes an analysis of model forecasts of the
onset of airmass fog. The paper goes on to describe future research in this area
15th Conference on Weather Analysis and Forecasting, August
Prediction of Ceilings and Visibility Using a Regional Scale Forecasting
Model
A study by Colorado State University outlining the use of the Regional Atmospheric
Modeling System (RAMS) and how it’s used to forecast 36-hour parameters such as
cloud base height, fractional cloudiness, and visibility primarily for use by
aviation forecasters
An Examination of the Mobile Bayway Fog Disaster
A post mortem examination of a significant fog event and a multi-vehicle chain reaction
accident on the Mobile Bay. Several exhibits dissect the causes of the fog and provides
hindsight observations of the NWS operations during the event.
Screened GOES-8 Multispectral (10.7 micron - 3.9 micron) Satellite Imagery to Detect
Stratus and Fog at Night
A study of the fog/stratus algorithm and its limitations and uses.
Towards The improved Prediction of Regional Fog Events
Analyzes a different approach to bracketing the hazard that fog poses. Two approaches are
offered: traditional and conceptual.
Toward More Accurate Terminal Forecasts of Stratus Burn Off Times for the San Francisco
International Airport
A study of the impact of low stratus in the Bay Area and efforts to more accurately forecast
stratus burn off to more closely match the peak demand times at the airport.
Short-Term High-Resolution Forecasting of Cloud Ceiling Heights and
Visibilities
A paper showing preliminary results of a study to improve short-term forecasting of
cloud ceiling heights and visibilities using the Penn State/NCAR mesoscale model
MM5. The paper expresses the need for more detailed and frequent weather
information
7th Conference on Aviation, Range, and Aerospace Meteorology, February
Cloud Layer Forecasting within the Local AWIPS MOS Program (LAMP)
Describes the LAMP program in detail and how it can be used to forecast ceiling
heights
Development of Algorithms to Objectively Forecast Present Weather and
Surface Visibility Using a Regional Numerical Model - An Update
A study to determine statistical relationships between raw model output and
observed weather parameters in order to devise an algorithm to be used for the U.S.
Air Force in its Theater Battle Management Program
Towards the Improved Prediction of Regional Fog Events
An investigative and operational methodology is described to improve the prediction
of regional fog formation, distribution, intensity and duration
User Sensitivity to Ceiling and Visibility and its Influence on Terminal Forecast
Verification
This paper describes the sensitivity for transport aviation users of the cost of inaccurate
terminal forecasts and discusses the difficulties in verifying TAFs. A brief discussion is
given showing that assumptions have to be made as to forecast interpretation before any
verification scheme can be derived. Two algorithms are shown and conclusions are offered.
8th Conference on Aviation, Range, and Aerospace Meteorology, January
Is the Meteogram a Forecaster's Tool for Fog and Wind at Vandenberg AFB, CA?
A report on the viability of the MM5 model to capture local wind and fog events. The summary
includes two rules of thumb for MM5 usage.
2nd Symposium on Environmental Applications, January
Contributions to a Baseline Understanding of the Impact of Weather on
Airline Carrier Operations
An approach to assessing the impact of various weather on airline carriers by
treating the problem on a national scale. This study compares monthly data on
carrier delays with a set of monthly average weather parameters (T/I)
16th International Conference on Interactive Information and Processing
Systems (IIPS) for Meteorology, Oceanography and Hydrology, January
Forecasts of Strong Wind and In-Cloud Icing for the Danish Great Belt
Bridge
A small-scale study on the effects of ice and wind on the Great Belt bridge
using simplified icing and wind models. This study has applications for low-level
aviation as well
Ceilometer Comparison March 1998-April 1999
Compares the Vaisala CT12K Ceilometer and human observers over a one year period
to determine the accuracy of the automated observation
NWS Western Region Aviation Workshop, May
Slide Presentations:
Aviation Weather Hazards Awareness Training
Aviation Weather Center Operations
9th Conference on Aviation, Range, and Aerospace Meteorology, September
Forecast Aids to Lessen the Impact of Marine Stratus on San Francisco
International Airport
A four year study into fog and stratus at SFO which has yielded several forecast
algorithms that will aid the operational forecasting of these events toward the
goal of mitigating delays they cause
Steps to Improve Ceiling and Visibility Forecasts for Aviation
A white paper discussing the steps necessary to improve the NWS ceiling and
visibility forecasts. The goal is to help the FAA reduce delays caused by over
pessimistic forecasts
National Weather Association 25th Annual Meeting, October
Satellite Images Provide Valuable Information Supplement to the Aviation
Meteorologist
An overview of satellite imagery and its relationship to aviation weather
forecasting in terms of turbulence and icing and ceiling and visibility. Excerpt
From an ICAO Journal article (T/I)
18th International Conference on Interactive Information and Processing
Systems (IIPS) for Meteorology, Oceanography and Hydrology, February
The Use of Artificial Intelligence Methods in Improved Visibility Forecasts
for Surface Transportation
A study undertaken by the National Highway Traffic Safety Administration defining
the use of artificial intelligence to forecast fog events to prevent surface
accidents. Two methods are used - case-based reasoning, and rule-based reasoning.
This has applications for the terminal aviation environment.
Visibility Variability at the Chicago O’Hare Airport: Insights into the
Impacts of Runway Visual Range (RVR) Measurements on Aviation Operations
Insights into how RVR factors into air traffic decision-making and how the data
should prove valuable for traffic planning leading to more effective operations.
ITWS Ceiling and Visibility Products, 1994
A study sponsored by the FAA outlining the products and technical developments of
the Integrated Terminal Weather System (ITWS) - a Doppler radar-based system for
the short-term forecasting in and around the airport environment. The ITWS system
can be used to forecast short-term ceiling and visibility events as shown in this
study
Mesoscale Numerical Prediction of Ceilings, Visibility, and Turbulence, 1996
A contractor’s report on the feasibility of producing a visibility, ceiling, and
turbulence model prediction system. The study includes rationale and approaches to
the problems inherent in numerical weather prediction in processing for these
events
Development of a Surface Visibility Algorithm for Worldwide Use with
Mesoscale Model Output, 1996
Categorized surface visibility equations with empirical corrections have been
developed for use in limited data environments with raw or mesoscale model out.
Verification results using a set of independently collected observations are
presented
Bulletin of the American Meteorological Society