DOCSLIB.ORG

Mist Netting Success in Relation to Weather by Susane

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Mist Netting Success in Relation to Weather by Susane Mist netting success in relation to weather By SusanE. Quinlan and RogerL. Boyd Introduction located 9.6 km northeast of the research site. Positionsof pressuresystems and weatherfronts Mist nets have often been used to quantify were obtained from the Daily Weather Maps avian populations;however, as Ralph (1976)has published by the National Oceanic and At- indicated,there are possiblevariables that need to mosphericAdministration. be correctedfor. Ralph (1976)provided a method to adjust for unequal net-hoursof operation to Number of birds captured during the morning equalizecomparisons between banding operations hours were comparedto the weather variables at andproposed the useof correctionvalues for vary- 0700 hours using a simple Pearson correlation ing lengthsof time for which the nets were run. statisticaltest. Weather variables include temper- These correctionvalues are basedon the assump- ature,barometric pressure, cloud cover, humidity tion that capture rates do not vary significantly and wind speed. over time.The numberof birds actuallycaptured, Since mostpasserines migrate at night (Lack1960, however, depends at least partially on two Kendeighet al. 1960,Nisbet and Drury 1968,and variables: the amount of bird activity and the Able 1973),the numbersof birdsmigrating through visibility of the nets.If birds are extremelyactive an area would be affectedby the weather during more birds will be captured.Or, if high humidity the night. To determine if capture successwas makes nets more visible, as suggestedby Stewart related to migrationmovements, the numbers of (1971),fewer birds will be caught.Stewart found birds mist netted on a given day was comparedto that peak mist net captureson cloudy days are pressuresystem and weatherfront locations and to significantlylater than on sunnydays. This implies individual weather variables at 0100 hours on the that weather affects bird activity or mist net previousnight. visibility.The purposeof thisstudy is to determine if mist nettingsuccess is affectedby the weather. Results and discussion Temperature, barometric pressure, and cloud Method coverwere associatedsignificantly (AOV, P•1.05) Researchwas conductedin SpringCreek Canyon, with the number of birds captured.Wind speed a small area of cottonwood habitat, 9.6 km and humidity did not show any correlationabove southwest of Fort Collins, Colorado. Black, 12 m- the .2 confidencelevel, again using analysisof long mist nets with a mesh size of 3.75 cm were variance. operatedover two periodsof ten consecutivedays Temperatureindicated a strongnegative correla- in the springsof 1973and 1975. In all, over450 birds tion with netting successat the 0.044 confidence of 42species were banded.Nets were operatedun- level. Thus, high temperatureswere associated til 0930hours each morning,and again from 1800 with low captures.Since the visibility of nets hoursuntil after dark each evening.Time of cap- would probably be unaffectedby temperature ture, species, age and sex classification,when alone, we assumed that temperature might be possible,were recordedbefore the bird was band- affectingthe activityperiod of birds.Eyster (1954) ed andreleased. Eleven nets were operatedin 1973 studiedthe activityperiod of captivesongbirds and and six in 1975. The six nets used in 1975 were in found that temperatureplays a significantrole in the same locations as six of the nets in 1973. The regulatingthe beginningand end of a bird's daily largernumber of netsused in 1973reflected utiliza- activityperiod. Althoughhe observedsome varia- tion of a largerportion of the SpringCreek Canyon tion amongspecies, Eyster found that an increase and did not indicate a greater number of nets in in temperaturebeyond a given point (normally the same area. 25øC)was generally associated with the end of the Most weather data were obtained from the morningactivity period. If thesesame associations Colorauo State University Experiment Station occurin wild birds, the end of the morningactivity Page 168 North American Bird Bander Vol. 1, No. 4 periodwould occurat an earlier time on mornings Accordingto many researchers(Kendeigh et al. with temperaturesabove 25øC than on cooler 1960,Lack 1960,Bagg 1965, Richardson 1971, Able mornings.Since the netswere operateduntil the 1973, and Emlen 1975) migration movementsof samelocal standardtime eachmorning, a variation birds are affected by weather variables. The in length of bird activity periods would be ex- possibilitywas consideredthat the resultsin this pectedto causea changein numberof birds cap- studymight only reflect the number of migrantsin tured. As might be expectedbased on Eyster's the studyarea. Thus, the numberof birdscaptured observations,low temperaturescorrelated with was comparedwith weather variables on the high capture success,and high temperaturescor- previousnight when passerinemigration would related with low capture success.This appearsto have occurred.As shownin Table I, no significant be a plausible explanation for the correlation correlations were observed at the 0.10 confidence observedbetween temperatureand captures. level. Barometric pressure was positively correlated with the numbers of birds captured at a TableI. Correlationstatistics resulting from comparison between the significancelevel of 0.037.The reasonfor this cor- numbers of mist netted birds and the weather variables at 0100 hours. relationis not apparent.Barometric pressure does not affect the visibility of the nets, so again, the Statistics Weathervariables possibilityof correlationswith the activity period TemperatureWind BarometricCloud Relative speed pressure cover humidity was investigated.There was no reference found in the literaturedirectly relating barometric pressure Correlation -I-.0570 -I-.0350 -+-.0980 -I-.1980 -I-.0234 to activityperiods of birds;however, one possibili- Coefficient ty is that periodsof high barometricpressure are Significance .717 .850 .560 .219 .890 alsoperiods of unfavorableweather conditionsfor Level migration (e.g., winds from the wrong direction [Richardson1971]). An increasednumber of cap- tures during these periods of unfavorable migrating conditions could be due to the birds Conclusions "holding over" in the study area until more favorable conditionsfor migration occur. More The results of this study show that mist netting researchis needed to verify or refute the existence successis affectedby weatherconditions along the of suchphenomena along the easternslope of the easternslope Colorado foothills. Thus, mist nets do ColoradoRocky Mountains. not givean accurateestimate of the relativedaily abundance of small land birds, as assumed by Cloud cover was also positivelycorrelated with Ralph 1976,Baird et al. 1958,and Baird et al. 1959. mist nettingssuccess at a 0.065significance level. However, if used over a longerperiod of time, as Stewart (1971)found that cloud cover causedan Weise (1971)did, the variationsin nettingsuccess hour delay in the peak of mist net captures. due to weathermight be overcome.Also, it should However, since the nets were operated past the be pointedout that the useof mistnets in calcula- times of peak capture reported by Stewart, this tion of a Lincoln-Petersonindex to populationsize, relationshipshould not affect the results. Most as suggestedby MacArthur and MacArthur (1974), probablyvisibility of netsis affectedby the amount wouldbe severelylimited by the effectsof weather of sunshine. Reflection of light, and thus net on mist netting success. visibility, will increase with the amount of sunlight.Thus, nets would be lessvisible on cloudy Summary days, and capture successwould be greater than on sunnydays. This would explain the positivecor- This studycompares number of mist nettedbirds relation observedbetween nettingsuccess and the with weather conditions. Simple correlation amount of cloud cover. statistics show associations between capture successand temperature, barometric pressure, No significantcorrelations between wind speedor and cloudcover. These correlations are explained humidity,0.314 and 0.358respectively, and capture success were observed. Both of these variables by the effectsof theseweather variables on net visibility and bird activity. No significantcor- would be expectedto increasethe visibility of nets relationswere foundbetween capture success and at somehigh level (i.e. 32 km per hour winds, or humidity and wind speed. relative humidity approaching 100 percent). However, suchextremes were not observedduring The possibilitythat thesecorrelations might result this study. from variations in numbers of migrants arriving Oct.-Dec. 1976 North American Bird Bander Page 169 with certain weather conditions is explored. Ralph, C.J. 1976.Standardization of mist net cap- However, no significantcorrelations were found tures for quantification of avian migration. between the number of mist netted birds and Bird-Banding47:44-47. weather variables during the night, the time at Richardson, W.J. 1971. Spring migration and which mostpasserine migration occurs. weather: a radar studyin easternCanada. Am. Birds 25:684-690. Stewart, B. 1971.Netting successin relation to time Acknowledgements of day and sunny versus overcast skies. W. Bird Bander 46:16-17. The authorsare gratefulto Jenifer S. Slaterfor her Weise, C.M. 1971. Relative abundance of small assistancein operating the mist nets in 1975. land birds in southeastWisconsin. Pass. Pigeon Further,we gratefullyacknowledge the assistance 33:173-188. of the ColoradoState University ExperimentSta- tion personneland Dr. John F. Benci for
Load more

Recommended publications
  • Performance Evaluation of Misting Fans in Hot and Humid Climate
    Building and Environment 45 (2010) 2666e2678 Contents lists available at ScienceDirect Building and Environment journal homepage: www.elsevier.com/locate/buildenv Performance evaluation of misting fans in hot and humid climate N.H. Wong*, Adrian Z.M. Chong Department of Building, School of Design and Environment, National University of Singapore, 117566 Republic of Singapore article info abstract Article history: Singapore experiences a hot and humid climate throughout the year. This in turn results in heavy reli- Received 3 March 2010 ance on mechanical systems especially air-conditioning to achieve thermal comfort. An alternative would Received in revised form be the use of evaporative cooling which is less energy intensive. Objective and subjective measurements 14 May 2010 were conducted at an experimental setup at the National University of Singapore (NUS) to evaluate the Accepted 27 May 2010 thermal conditions and thermal sensations brought about by misting fans. Field measurements were also conducted at food centres in Singapore to determine if they are coherent with the objective and Keywords: subjective measurements conducted. Analysis of objective and subjective data showed that the misting Misting fan fi Evaporative cooling fan was able to signi cantly reduce the dry-bulb temperature and thermal sensation votes. This is fi Singapore consistent with eld measurements taken, where regression analysis showed that with the misting fan, Hot thermal neutrality can be obtained at a higher outdoor effective temperature (ET*). However, the Humid reduction in temperature comes at the expense of higher relative humidity which results in consistently greater biological (bacterial and fungal) pollutants being enumerated from samples collected under the misting fan system.
    [Show full text]
  • Aerodrome Actual Weather – METAR Decode
    Aerodrome Actual Weather – METAR decode Code element Example Decode Notes 1 Identification METAR — Meteorological Airfield Report, SPECI — selected special (not from UK civil METAR or SPECI METAR METAR aerodromes) Location indicator EGLL London Heathrow Station four-letter indicator 'ten twenty Zulu on the Date/Time 291020Z 29th' AUTO Metars will only be disseminated when an aerodrome is closed or at H24 aerodromes, A fully automated where the accredited met. observer is on duty break overnight. Users are reminded that reports AUTO report with no human of visibility, present weather and cloud from automated systems should be treated with caution intervention due to the limitations of the sensors themselves and the spatial area sampled by the sensors. 2 Wind 'three one zero Wind degrees, fifteen knots, Max only given if >= 10KT greater than the mean. VRB = variable. 00000KT = calm. 31015G27KT direction/speed max twenty seven Wind direction is given in degrees true. knots' 'varying between two Extreme direction 280V350 eight zero and three Variation given in clockwise direction, but only when mean speed is greater than 3 KT. variance five zero degrees' 3 Visibility 'three thousand two Prevailing visibility 3200 0000 = 'less than 50 metres' 9999 = 'ten kilometres or more'. No direction is required. hundred metres' Minimum visibility 'Twelve hundred The minimum visibility is also included alongside the prevailing visibility when the visibility in one (in addition to the 1200SW metres to the south- direction, which is not the prevailing visibility, is less than 1500 metres or less than 50% of the prevailing visibility west' prevailing visibility. A direction is also added as one of the eight points of the compass.
    [Show full text]
  • Indoor Air Quality in Commercial and Institutional Buildings
    Indoor Air Quality in Commercial and Institutional Buildings OSHA 3430-04 2011 Occupational Safety and Health Act of 1970 “To assure safe and healthful working conditions for working men and women; by authorizing enforcement of the standards developed under the Act; by assisting and encouraging the States in their efforts to assure safe and healthful working conditions; by providing for research, information, education, and training in the field of occupational safety and health.” This publication provides a general overview of a particular standards-related topic. This publication does not alter or determine compliance responsibili- ties which are set forth in OSHA standards, and the Occupational Safety and Health Act of 1970. More- over, because interpretations and enforcement poli- cy may change over time, for additional guidance on OSHA compliance requirements, the reader should consult current administrative interpretations and decisions by the Occupational Safety and Health Review Commission and the courts. Material contained in this publication is in the public domain and may be reproduced, fully or partially, without permission. Source credit is requested but not required. This information will be made available to sensory- impaired individuals upon request. Voice phone: (202) 693-1999; teletypewriter (TTY) number: 1-877- 889-5627. Indoor Air Quality in Commercial and Institutional Buildings Occupational Safety and Health Administration U.S. Department of Labor OSHA 3430-04 2011 The guidance is advisory in nature and informational in content. It is not a standard or regulation, and it neither creates new legal obligations nor alters existing obligations created by OSHA standards or the Occupational Safety and Health Act.
    [Show full text]
  • Protecting Against Vapor Explosions with Water Mist
    PROTECTING AGAINST VAPOR EXPLOSIONS WITH WATER MIST J. R. Mawhinney and R. Darwin Hughes Associates, Inc. INTRODUCTION This paper examines a number of practical questions about the possibility of using water mist to mitigate explosion hazards in some industrial applications. Water mist systems have been installed to replace Halon 1301 in gas compressor modules on Alaska’s North Slope oil fields. The hazard in the compressor modules includes fire in lubrication oil lines for the gas turbines that drive the compressors. The hazard also involves the potential for a methane gas leak, ignition, and explosion, although the probabilities of occurrence for the explosion hazard are not the same as the lube oil fire. The performance objective for the original halon systems was to inert the compartment, thus addressing both fire and explosion concerns. The design concentra- tions for the compressor modules were closer to 1.5% than to S%, indicating they were intended to provide an inerting effect. As part of the global move to eliminate ozone-depleting fire sup- pression agents, companies are replacing Halon 1301 systems with water mist systems. The water mist systems were developed and tested for control of liquid fuel or lubricating oil spray or pool fires associated with the turbines that drive the gas compressors. The water mist systems address the most likely hazard, the lube oil fire, hut the inerting benefit provided by Halon I301 has been lost. This has left the question of what to do if there is a methane gas leak unanswered. The question has been asked by the operators of these modules as to whether water mist can provide any benefit for mitigating the gas-air explosion hazard.
    [Show full text]
  • Information Contained in a METAR Example METAR Codes
    METAR METAR is a format for reporting weather information. A METAR weather report is predominantly used by pilots in fulfillment of a part of a pre-flight weather briefing, and by meteorologists, who use aggregated METAR information to assist in weather forecasting. Raw METAR is the most common format in the world for the transmission of observational weather data. [citation needed] It is highly standardized through the International Civil Aviation Organization (ICAO), which allows it to be understood throughout most of the world. Information contained in a METAR A typical METAR contains data for the temperature, dew point, wind speed and direction, precipitation, cloud cover and heights, visibility, and barometric pressure. A METAR may also contain information on precipitation amounts, lightning, and other information that would be of interest to pilots or meteorologists such as a pilot report or PIREP, colour states and runway visual range (RVR). In addition, a short period forecast called a TRED may be added at the end of the METAR covering likely changes in weather conditions in the two hours following the observation. These are in the same format as a Terminal Aerodrome Forecast (TAF). The complement to METARs, reporting forecast weather rather than current weather, are TAFs. METARs and TAFs are used in VOLMET broadcasts. Example METAR codes International METAR codes The following is an example METAR from Burgas Airport in Burgas, Bulgaria. It was taken on 4 February 2005 at 16:00 Coordinated Universal Time (UTC). METAR LBBG 041600Z 12003MPS 310V290 1400 R04/P1500 R22/P1500U +S BK022 OVC050 M04/M07 Q1020 OSIG 9949//91= • METAR indicates that the following is a standard hourly observation.
    [Show full text]
  • Key to Aerodrome Forecast (TAF) and Aviation Routine Weather Report (METAR) (Front)
    Key to Aerodrome Forecast (TAF) and Aviation Routine Weather Report (METAR) (Front) KEY to AERODROME FORECAST (TAF) and U.S. Department of Transportation AVIATION ROUTINE WEATHER REPORT Federal Aviation (METAR) (FRONT) Administration TAF KPIT 091730Z 091818 15005KT 5SM HZ FEW020 WS010/31022KT FM 1930 30015G25KT 3SM SHRA OVC015 TEMPO 2022 1/2SM +TSRA OVC008CB FM0100 27008KT 5SM SHRA BKN020 OVC040 PROB40 0407 1SM -RA BR FM1015 18005KT 6SM -SHRA OVC020 BECMG 1315 P6SM NSW SKC METAR KPIT 091955Z COR 22015G25KT 3/4SM R28L/2600FT TSRA OVC010CB 18/16 A2992 RMK SLP045 T01820159 FORECAST EXPLANATION REPORT TAF Message type : TAF-routine or TAF AMD-amended forecast, METAR METAR-hourly, SPECI-special or TESTM-non-commissioned ASOS report KPIT ICAO location indicator KPIT 091730Z Issuance time: ALL times in UTC “Z”, 2-digit date, 4-digit time 091955Z 091818 Valid period: 2-digit date, 2-digit beginning, 2-digit ending times In U.S. METAR: CORrected of; or AUTOmated ob for automated COR report with no human intervention; omitted when observer logs on 15005KT Wind: 3 digit true-north direction , nearest 10 degrees (or VaRiaBle); 22015G25KT next 2-3 digits for speed and unit, KT (KMH or MPS); as needed, Gust and maximum speed; 00000KT for calm; for METAR, if direction varies 60 degrees or more, Variability appended, e.g., 180V260 5SM Prevailing visibility; in U.S., Statute Miles & fractions; above 6 miles in 3/4SM TAF Plus6SM. (Or, 4-digit minimum visibility in meters and as required, lowest value with direction) Runway Visual Range: R; 2-digit runway designator Left, Center, or R28L/2600FT Right as needed; “/”, Minus or Plus in U.S., 4-digit value, FeeT in U.S., (usually meters elsewhere); 4-digit value Variability 4-digit value (and tendency Down, Up or No change) HZ Significant present, forecast and recent weather: see table (on back) TSRA FEW020 Cloud amount, height and type: SKy Clear 0/8, FEW >0/8-2/8, OVC 010CB SCaTtered 3/8-4/8, BroKeN 5/8-7/8, OVerCast 8/8; 3-digit height in hundreds of ft; Towering CUmulus or CumulonimBus in METAR; in TAF, only CB.
    [Show full text]
  • Metar Abbreviations Metar/Taf List of Abbreviations and Acronyms
    METAR ABBREVIATIONS http://www.alaska.faa.gov/fai/afss/metar%20taf/metcont.htm METAR/TAF LIST OF ABBREVIATIONS AND ACRONYMS $ maintenance check indicator - light intensity indicator that visual range data follows; separator between + heavy intensity / temperature and dew point data. ACFT ACC altocumulus castellanus aircraft mishap MSHP ACSL altocumulus standing lenticular cloud AO1 automated station without precipitation discriminator AO2 automated station with precipitation discriminator ALP airport location point APCH approach APRNT apparent APRX approximately ATCT airport traffic control tower AUTO fully automated report B began BC patches BKN broken BL blowing BR mist C center (with reference to runway designation) CA cloud-air lightning CB cumulonimbus cloud CBMAM cumulonimbus mammatus cloud CC cloud-cloud lightning CCSL cirrocumulus standing lenticular cloud cd candela CG cloud-ground lightning CHI cloud-height indicator CHINO sky condition at secondary location not available CIG ceiling CLR clear CONS continuous COR correction to a previously disseminated observation DOC Department of Commerce DOD Department of Defense DOT Department of Transportation DR low drifting DS duststorm DSIPTG dissipating DSNT distant DU widespread dust DVR dispatch visual range DZ drizzle E east, ended, estimated ceiling (SAO) FAA Federal Aviation Administration FC funnel cloud FEW few clouds FG fog FIBI filed but impracticable to transmit FIRST first observation after a break in coverage at manual station Federal Meteorological Handbook No.1, Surface
    [Show full text]
  • Indoor Air Quality
    Indoor Air Quality FILL YOUR HOME WITH AIR THAT IS AS CLEAN AS IT IS COMFORTABLE. FRESHER AIR. A VALUE VENTILATION OPTION WITH INTELLIGENT LOGIC The Envirowise™ Energy Recovery Ventilator (ERV) exchanges stale, indoor air and provides heated and humidified fresh air in a more efficient and The EnviroWise™ QF130V in-line ventilator offers a cost effective mechanical fresh consistent manner than opening a window. In the winter, heat and moisture air solution that controls humidity and temperature. The QF130V has a full ECM are transferred from the exhaust air back into the incoming fresh air. In the motor that makes installation fast and easy, with no balancing dampers required. summer, Envirowise ERV removes heat and moisture from outdoor air to The ECM motor allows for adjustable airflow to meet the ventilation requirements for provide fresh, cooled, dehumidified air to your home. homes up to 3500 sq. ft. The installer dials in the quantity (CFM) of fresh air needed and sets the desired limits for outside humidity and temperature, and the QF130V is ready. A 24V relay is included with the unit and allows the flexibility of controlling 5 the QF130V from a wall mounted thermostat. 4 Outdoor Air Stale Air Sent Outdoors 1 Heat and Stale Indoor Air 2 Fresh Air Moisture Transfer Sent Indoors 1 62.2 Compliant Ventilation With adjustable airflow from 30 to 3 1 130 cfm to meet ventilation codes for all size homes. 2 MERV 8 filter 6 Included for improved indoor air quality. Optional heater available for extreme cold climates 3 On-board LCD “logic” controller Why is the Envirowise ERV good for your 1 High efficiency crossflow energy transfer core Allows for customized set-up home and your family? High-performance core recovers heat and moisture from depending on climate conditions.
    [Show full text]
  • Mist Collection of Metalworking Fluids How to Control, Contain, and Filter Coolant & Oil Mist a Technical Reference Guide Table of Contents
    MIST COLLECTION OF METALWORKING FLUIDS HOW TO CONTROL, CONTAIN, AND FILTER COOLANT & OIL MIST A TECHNICAL REFERENCE GUIDE TABLE OF CONTENTS WHY Mist Collection? ................................................................................. 4 Start with the Basics .................................................................................. 4 What is Mist? .....................................................................................................................4 What is Smoke? ................................................................................................................4 History of Mist Collection .................................................................................................5 Steps to Selecting the Right Mist Collector ....................................................................6 1. Determine Your Needs ........................................................................... 6 1A. Types of Machines Generating Mist ....................................................................6 Metal Cutting Operations – Mills .........................................................................6 Metal Cutting Operations – Turning ....................................................................7 Metal Grinding Operations ...................................................................................7 Metal Forming Operations – Heading and Stamping ........................................8 Metal Forming Operations – Casting ...................................................................8
    [Show full text]
  • Fog9 Mist, Dew3 Und Other Sources of Wuter
    Fog, Mist, Dew, and Other Sources of Water 103 Fog9 Mist, Dew3 In the first place, the dew water could run ofi" the leaves and collect in und Other Sources the soil on which it drips. The amount of Wuter of dew, however, is too small to wet more than a few millimeters of the soil. In the second place, it is possible F. W. Went that the dew water is absorbed by the leaf surface, on which it condenses, and The main sources of water for crops thus is used directly by the plant. That in most agricultural areas are rain or was found to be the case; young leaves irrigation. In many parts of the world, especially can absorb the dew as rapid- however, neither rain nor ground wa- ly as it forms. One can often observe ter seems to be enough to account for that after a night of heavy dew the the development of the naturally oc- young leaves of shrubs and herbs are curring vegetation. In those places we quite dry and the older ones are cov- have to look for other sources of wa- ered with dew. This absorbed water ter—fog, mist, and dew—and their can be moved to other parts of the possible contribution to plant growth. plant and can even be excreted by the On many days and in many locali- roots into the soil. Such water would ties, plants are covered with dew in be available again the next day. It was the early morning. Because dew dis- actually found that the soil around root appears soon after sunrise, people often systems of plants is more moist when overlooked it as a possible source of they are subjected to dew than around water, which they consider to be most roots of plants that do not receive dew, necessary in midday.
    [Show full text]
  • Forecasting Fog and Stratus in Aviation Weather Service
    Forecasting fog and stratus in aviation weather service About formation and dissipation of fog and stratus, their occurrence around the year and effects on the airport services in Finland. 3.12.2018 Aviation Event Week EUMeTrain Elina Tuhkalainen Where do you come from? Elina Tuhkalainen Meteorologist at Aviation and Military Weather Services, Finnish Meteorological Institute 2 Click your arrow in the group you belong to: Aviation forecasters Other forecasters Other 3 Content • Fog types, definitions • Formation and dissipation • Occurrence of fog and stratus around the year (examples in Finland) • Orography effects • Tools we’re using to forecast stratus and fog • Effects on the airport • Case studies 4 Definitions • Fog and mist • High humidity reduces visibility • 1-5 km: mist • ≤ 1 km: fog • Stratus • Low cloud Hannu Manninen • Base 0-1000 ft (approx. 300 m) • On ground fog • TAF codes: • FG - fog • BR - mist • MIFG - shallow fog (≤ 2 m) • PRFG - partial fog • BCFG - paches of fog • FZFG - freezing fog (T ≤ 0oC) Eija Vallinheimo 5 Formation and dissipation • Interaction between the air and the ground • Formation: The air cools down or becomes more moist • Dissipation of fog: air warms up or dries • Radiation: cools the ground and the air (sunrise, sunset) • Advection: brings cold air over moist surface • Rain: can either clean the fog or make the low levels more humid and thus lower the ceiling • Cloudiness above the fog: • Higher clouds may slow down the dissipation • It can also prevent the fog to develop Juval6 Cohen Warm and moist air Warm Cold (moist) Cold ground air air (or water) Radiation: Advection: Warm and cold air • Clear night • Warm and moist air moves on mixing • T decreases cold ground • Reverse: cold air over warm water Warm water Cold ground Warm fog Cold Reijo Hyvönen o Orography Warm front: Very cold air (<-20 C): Warm precipitation falls • Water vapour into cold air condenses into ice crystals 7 8 9 Fog around the year at EFHK (Helsinki-Vantaa airport, Finland) Day of month 1.
    [Show full text]
  • By Peg Zenko
    by Peg Zenko Shrouds of gauze, creeping fingers across fields at dusk, a wall hiding nefarious events in mystery novels and scary movies: Fog fascinates us and stirs our imaginations. It has the ability to soften an otherwise harsh scene, to call into action the Fresnel Lenses of the Great Lakes lighthouses, make fantastic shadows of ordinary objects, and create stunning optical effects. Fog is, by WBAN (Weather Bureau, Air Force, and Navy) definition, the same as a cloud, but with its base close enough to the earth that it restricts visibility to less than 1 kilometer, or .62 miles. In the panoramic view below, we were driving into a thick bank of upslope fog in western Montana that was a lower extension of the clouds above a range in the Rocky Mountains. The peaks are about 8000 feet above sea level. Many manifestations of fog exist, and each has their own aesthetic characteristics. We can find descriptions of fog types in The AMS Glossary of Meteorology; that does not describe changes to the context of a scene. http://amsglossary.allenpress.com/glossary Fog is produced in a variety of ways. Advection fog is the result of moist air passing over a cold surface, commonly seen in our area over the water of Green Bay. Radiation fog forms over land when the air temperature falls below the dew point, and can manifest itself in thick “pea soup” hazardous driving conditions on a clear sky night. Steam fog is a com- mon sight in fall, the result of very cold air flowing over relatively warm water.
    [Show full text]