Documentation for Selected Reference Tables in the Archive Database Version 1.0 October 9, 2002
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Winter Precipitation Liquid–Ice Phase Transitions Revealed with Polarimetric Radar and 2DVD Observations in Central Oklahoma
MAY 2017 B U K O V CICETAL. 1345 Winter Precipitation Liquid–Ice Phase Transitions Revealed with Polarimetric Radar and 2DVD Observations in Central Oklahoma PETAR BUKOVCIC ´ NOAA/National Severe Storms Laboratory, and Cooperative Institute for Mesoscale Meteorological Studies, and School of Meteorology, and Advanced Radar Research Center, University of Oklahoma, Norman, Oklahoma DUSAN ZRNIC´ NOAA/National Severe Storms Laboratory, Norman, Oklahoma GUIFU ZHANG School of Meteorology, and Advanced Radar Research Center, University of Oklahoma, Norman, Oklahoma (Manuscript received 30 June 2016, in final form 8 November 2016) ABSTRACT Observations and analysis of an ice–liquid phase precipitation event, collected with an S-band polarimetric KOUN radar and a two-dimensional video disdrometer (2DVD) in central Oklahoma on 20 January 2007, are presented. Using the disdrometer measurements, precipitation is classified either as ice pellets or rain/freezing rain. The disdrometer observations showed fast-falling and slow-falling particles of similar size. The vast majority (.99%) were fast falling with observed velocities close to those of raindrops with similar sizes. In contrast to the smaller particles (,1 mm in diameter), bigger ice pellets (.1.5 mm) were relatively easy to distinguish because their shapes differ from the raindrops. The ice pellets were challenging to detect by looking at conventional polarimetric radar data because of the localized and patchy nature of the ice phase and their occurrence close to the ground. Previously published findings referred to cases in which ice pellet areas were centered on the radar location and showed a ringlike structure of enhanced differential reflectivity ZDR and reduced copolar correlation coefficient rhv and horizontal reflectivity ZH in PPI images. -
Downloaded 10/01/21 08:52 PM UTC 186 WEATHER and FORECASTING VOLUME 16
FEBRUARY 2001 NOTES AND CORRESPONDENCE 185 Further Investigation of a Physically Based, Nondimensional Parameter for Discriminating between Locations of Freezing Rain and Ice Pellets ROBERT M. RAUBER,LARRY S. OLTHOFF, AND MOHAN K. RAMAMURTHY Department of Atmospheric Sciences, University of Illinois at Urbana±Champaign, Urbana, Illinois KENNETH E. KUNKEL Midwestern Climate Center, Illinois State Water Survey, Champaign, Illinois 9 December 1999 and 16 August 2000 ABSTRACT The general applicability of an isonomogram developed by Czys and coauthors to diagnose the position of the geographic boundary between freezing precipitation (freezing rain or freezing drizzle) and ice pellets (sleet or snow grains) was tested using a 25-yr sounding database consisting of 1051 soundings, 581 where stations were reporting freezing drizzle, 391 reporting freezing rain, and 79 reporting ice pellets. Of the 1051 soundings, only 306 clearly had an environmental temperature and moisture pro®le corresponding to that assumed for the isonomogram. This pro®le consisted of a three-layer atmosphere with 1) a cold cloud layer aloft that is a source of ice particles, 2) a midlevel layer where the temperature exceeds 08C and ice particles melt, and 3) a surface layer where T , 08C. The remaining soundings did not conform to the pro®le either because 1) the freezing precipitation was associated with the warm rain process or 2) the ice pellets formed due to riming rather than melting and refreezing. For soundings conforming to the pro®le, the isonomogram showed little diagnostic skill. Freezing rain or freezing drizzle occurred about 50% of the time that ice pellets were expected. -
News and Notes
346 BULLETIN AMERICAN METEOROLOGICAL SOCIETY NEWS AND NOTES Air Force Scientists Develop Technique The feasibility of dissipating supercooled clouds by for Cutting Holes in "Cold" Clouds seeding with dry-ice was recognized many years ago. Airborne equipment, previously developed to do this, A new technique for creating holes in supercooled cloud crushed large blocks of dry-ice into particles suitable for layers has been developed by Air Force Cambridge Re- seeding purposes. search Laboratories scientists. During recent flight tests This equipment had two particular limitations. First, using this technique, holes more than 3 miles wide were these machines produced about half powdered dry-ice created in supercooled clouds. which evaporated immediately upon dispersal from the Major James F. Church, project scientist in AFCRL's aircraft and was wasted. Second, the logistical problem Meteorological Research Laboratory is directing research of supplying enough dry-ice where needed and the high on the dissipation of supercooled stratiform clouds. The evaporational losses suffered during storage until used, program is under the technical management of the Air severely limited the utility of this technique. Force System Command's Electronic Systems Division. The Cloudbuster makes ice pellets by passing liquid The principal objective of this research is to provide C02 through an expansion nozzle and then compacting Air Force cargo and transport pilots with an economical the solid dry-ice powder, which is then formed, into proper capability to seed supercooled clouds with dry-ice pellets, size. The Cloudbuster has been designed with the capa- made on the aircraft and dispersed at will, to create bility of making different-sized pellets at the touch of a sizable holes in such cloud decks. -
The Weather the Weather
The weather Área Lectura y Escritura Resultados de aprendizaje Conocer vocabulario relacionado al clima. Utilizar vocabulario relacionado al clima en contextos de escritura formal. Contenidos 1. General vocabulary words Debo saber - Simple present - Present continuous - Simple past - Past continuous The Weather Cold weather In Scandinavia, the chilly (1) days of autumn soon change to the cold days of winter. The first frosts (2) arrive and the roads become icy. Rain becomes sleet (3) and then snow, at first turning to slush (4) in the streets, but soon settling (5), with severe blizzards (6) and snowdrifts (7) in the far north. Freezing weather often continues in the far north until May or even June, when the ground starts to thaw (8) and the ice melts (9) again. - (1) cold, but not very - (2) thin white coat of ice on everything - (3) rain and snow mixed - (4) dirty, brownish, half- snow, half – water - (5) staying as a white covering - (6) snow blown by high winds - (7) Deep banks of snow against walls, etc. - (8) change from hard, frozen state to normal - (9) change from solid to liquid under heat Servicios Académicos para el Acompañamiento y la Permanencia - PAIEP Primera Edición - 2016 En caso de encontrar algún error, contáctate con PAIEP-USACH al correo: [email protected] 1 Warm / hot weather - Close: warm and uncomfortable. - Stifling: hot, uncomfortable, you can hardly breathe. - Humid: hot and damp, makes you sweat a lot. - Scorching: very hot, often used in positive contexts. - Boling: very hot, often used in negative contexts - Mild: warm at a time when it is normally cold - Heat wave last month: very hot, dry period Wet weather This wet weather scale gets stronger from left to right. -
WMO Solid Precipitation Measurement Intercomparison--Final Report
W O R L D M E T E O R O L O G I C A L O R G A N I Z A T I O N INSTRUMENTS AND OBSERVING METHODS R E P O R T No. 67 WMO SOLID PRECIPITATION MEASUREMENT INTERCOMPARISON FINAL REPORT by B.E. Goodison and P.Y.T. Louie (both Canada) and D. Yang (China) WMO/TD - No. 872 1998 NOTE The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the World Meteorological Organization concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. This report has been produced without editorial revision by the WMO Secretariat. It is not an official WMO publication and its distribution in this form does not imply endorsement by the Organization of the ideas expressed. FOREWORD The WMO Solid Precipitation Measurement Intercomparison was started in the northern hemisphere winter of 1986/87. The field work was carried out in 13 Member countries for seven years. The Intercomparison was the result of Recommendation 17 of the ninth session of the Commission for Instruments and Methods of Observation (CIMO-IX). As in previous WMO intercomparisons of rain gauges, the main objective of this test was to assess national methods of measuring solid precipitation against methods whose accuracy and reliability were known. It included past and current procedures, automated systems and new methods of observation. The experiment was designed to determine especially wind related errors, and wetting and evaporative losses in national methods of measuring solid precipitation. -
Student Name: ______Date: ______
Water Cycle Vocabulary Worksheet Student Name: _______________________ Date: _________ Teacher Name: LaTrecia Abero Score: _________ Define these terms: Atmosphere The different layers of gases that extend from the surface of the Earth into space. Boiling This is the change from a liquid to a gas. Boiling Point This is a temperature where the vapor pressure of a liquid equals the atmospheric pressure. Cloud The result of evaporation, this is a visible body of fine water droplets or ice particles suspended in Earth's atmosphere. Condensation This is the process of matter changing from a gaseous state to a liquid state. Dew This is when water vapor in the air condenses directly onto a surface, usually seen in the morning. Earth The third planet from the sun. Evaporation This is another term for vaporization, the part of the water cycle in which water changes from a liquid to a gas. Water moves from bodies of water on Earth to water vapor in the atmosphere. Fog This is a low-lying cloud. This is a collection of liquid water droplets or ice crystals suspended in the air at or near the Earth's surface. Freezing This is the process of matter changing from the liquid to the solid state. Groundwater This is water stored in the spaces between rocks inside Earth that is found within a few miles of the Earth's surface. Hail This is pellets of frozen rain that fall in showers from cumulonimbus clouds. Heat The transfer of thermal energy between two bodies which are at different temperatures. The SI unit for this is the Joule. -
METAR/SPECI Reporting Changes for Snow Pellets (GS) and Hail (GR)
U.S. DEPARTMENT OF TRANSPORTATION N JO 7900.11 NOTICE FEDERAL AVIATION ADMINISTRATION Effective Date: Air Traffic Organization Policy September 1, 2018 Cancellation Date: September 1, 2019 SUBJ: METAR/SPECI Reporting Changes for Snow Pellets (GS) and Hail (GR) 1. Purpose of this Notice. This Notice coincides with a revision to the Federal Meteorological Handbook (FMH-1) that was effective on November 30, 2017. The Office of the Federal Coordinator for Meteorological Services and Supporting Research (OFCM) approved the changes to the reporting requirements of small hail and snow pellets in weather observations (METAR/SPECI) to assist commercial operators in deicing operations. 2. Audience. This order applies to all FAA and FAA-contract weather observers, Limited Aviation Weather Reporting Stations (LAWRS) personnel, and Non-Federal Observation (NF- OBS) Program personnel. 3. Where can I Find This Notice? This order is available on the FAA Web site at http://faa.gov/air_traffic/publications and http://employees.faa.gov/tools_resources/orders_notices/. 4. Cancellation. This notice will be cancelled with the publication of the next available change to FAA Order 7900.5D. 5. Procedures/Responsibilities/Action. This Notice amends the following paragraphs and tables in FAA Order 7900.5. Table 3-2: Remarks Section of Observation Remarks Section of Observation Element Paragraph Brief Description METAR SPECI Volcanic eruptions must be reported whenever first noted. Pre-eruption activity must not be reported. (Use Volcanic Eruptions 14.20 X X PIREPs to report pre-eruption activity.) Encode volcanic eruptions as described in Chapter 14. Distribution: Electronic 1 Initiated By: AJT-2 09/01/2018 N JO 7900.11 Remarks Section of Observation Element Paragraph Brief Description METAR SPECI Whenever tornadoes, funnel clouds, or waterspouts begin, are in progress, end, or disappear from sight, the event should be described directly after the "RMK" element. -
The Mesoscale Dynamics of Freezing Rain Storms Over Eastern Canada
VOL. 56, NO.10 JOURNAL OF THE ATMOSPHERIC SCIENCES 15 MAY 1999 The Mesoscale Dynamics of Freezing Rain Storms over Eastern Canada K. K. SZETO Climate Processes and Earth Observation Division, Atmospheric Environment Service, Downsview, Ontario, Canada A. TREMBLAY Cloud Physics Research Division, Atmospheric Environment Service, Dorval, Quebec, Canada H. GUAN AND D. R. HUDAK Cloud Physics Research Division, Atmospheric Environment Service, Downsview, Ontario, Canada R. E. STEWART AND Z. CAO Climate Processes and Earth Observation Division, Atmospheric Environment Service, Downsview, Ontario, Canada (Manuscript received 2 June 1997, in ®nal form 9 June 1998) ABSTRACT A severe ice storm affected the east coast of Canada during the Canadian Atlantic Storms Project II. A hierarchy of cloud-resolving model simulations of this storm was performed with the objective of enhancing understanding of the cloud and mesoscale processes that affected the development of freezing rain events. The observed features of the system were reasonably well replicated in the high-resolution simulation. Diagnosis of the model results suggests that the change of surface characteristics from ocean to land when the surface warm front approaches Newfoundland disturbs the (quasi-) thermal wind balance near the frontal region. The cross-frontal circulation intensi®es in response to the thermal wind imbalance, which in turn leads to the development of an extensive above-freezing inversion layer in the model storm. Depending on the depth of the subfreezing layer below the inversion, the melted snow may refreeze within the subfreezing layer to form ice pellets or they may refreeze at the surface to form freezing rain. Such evolution of surface precipitation types in the model storm was reasonably well simulated in the model. -
ESSENTIALS of METEOROLOGY (7Th Ed.) GLOSSARY
ESSENTIALS OF METEOROLOGY (7th ed.) GLOSSARY Chapter 1 Aerosols Tiny suspended solid particles (dust, smoke, etc.) or liquid droplets that enter the atmosphere from either natural or human (anthropogenic) sources, such as the burning of fossil fuels. Sulfur-containing fossil fuels, such as coal, produce sulfate aerosols. Air density The ratio of the mass of a substance to the volume occupied by it. Air density is usually expressed as g/cm3 or kg/m3. Also See Density. Air pressure The pressure exerted by the mass of air above a given point, usually expressed in millibars (mb), inches of (atmospheric mercury (Hg) or in hectopascals (hPa). pressure) Atmosphere The envelope of gases that surround a planet and are held to it by the planet's gravitational attraction. The earth's atmosphere is mainly nitrogen and oxygen. Carbon dioxide (CO2) A colorless, odorless gas whose concentration is about 0.039 percent (390 ppm) in a volume of air near sea level. It is a selective absorber of infrared radiation and, consequently, it is important in the earth's atmospheric greenhouse effect. Solid CO2 is called dry ice. Climate The accumulation of daily and seasonal weather events over a long period of time. Front The transition zone between two distinct air masses. Hurricane A tropical cyclone having winds in excess of 64 knots (74 mi/hr). Ionosphere An electrified region of the upper atmosphere where fairly large concentrations of ions and free electrons exist. Lapse rate The rate at which an atmospheric variable (usually temperature) decreases with height. (See Environmental lapse rate.) Mesosphere The atmospheric layer between the stratosphere and the thermosphere. -
Tornadoes Family Activity Sheets
A Tornado Is Born Page 1 of 3 Name ________________________________________________________________________ Step 1: Use books, the Internet and other resources to define each of the words below. If possible, draw a picture of the word to help others understand its meaning. anvil cloud: atmosphere: condense: cumulus cloud: cumulonimbus cloud: downdraft: front: funnel cloud: mesocyclone: supercell: thunderhead: updraft: vortex: vertical wind shear: A TORNADO IS BORN Visit the American Red Cross Web site Masters of Disaster® Tornadoes, Level 2 at www.redcross.org/disaster/masters Copyright 2007 The American National Red Cross A Tornado Is Born Page 2 of 3 Step 2: Below is a description of the way tornadoes form. Some of the words are missing. Use the words from Step 1 to complete the description. Then, draw a story- board on the back of the page showing the formation of a tornado. High in the _______________, cool air pushes against warm air. The place where the two kinds of air meet is called a ______. A front can stretch over 100 miles (161 kilo- meters). On warm days, the air near the ground is much warmer than it is at higher eleva- tions. Warm air rises by bubbling up from the ground, just like the bubbles in a pot of boiling water. If the air has enough moisture in it, the moisture ____________ and forms ____________________. Sometimes, the rising air is trapped by a layer of cooler air above it. As the day continues, the warm air builds up. If this pocket of warm air rises quickly, it can break through the cap of cooler air like water shooting up from a fountain and a __________________, or _________________ (kyu-mya-lo-NIM-buhs) cloud grows, topped by an ____________. -
Print Key. (Pdf)
Weather Map Symbols Along the center, the cloud types are indicated. The top symbol is the high-level cloud type followed by the At the upper right is the In the upper left, the temperature mid-level cloud type. The lowest symbol represents low-level cloud over a number which tells the height of atmospheric pressure reduced to is plotted in Fahrenheit. In this the base of that cloud (in hundreds of feet) In this example, the high level cloud is Cirrus, the mid-level mean sea level in millibars (mb) A example, the temperature is 77°F. B C C to the nearest tenth with the cloud is Altocumulus and the low-level clouds is a cumulonimbus with a base height of 2000 feet. leading 9 or 10 omitted. In this case the pressure would be 999.8 mb. If the pressure was On the second row, the far-left Ci Dense Ci Ci 3 Dense Ci Cs below Cs above Overcast Cs not Cc plotted as 024 it would be 1002.4 number is the visibility in miles. In from Cb invading 45° 45°; not Cs ovcercast; not this example, the visibility is sky overcast increasing mb. When trying to determine D whether to add a 9 or 10 use the five miles. number that will give you a value closest to 1000 mb. 2 As Dense As Ac; semi- Ac Standing Ac invading Ac from Cu Ac with Ac Ac of The number at the lower left is the a/o Ns transparent Lenticularis sky As / Ns congestus chaotic sky Next to the visibility is the present dew point temperature. -
Cloud Microphysics
Cloud microphysics Claudia Emde Meteorological Institute, LMU, Munich, Germany WS 2011/2012 Growth Precipitation Cloud modification Overview of cloud physics lecture Atmospheric thermodynamics gas laws, hydrostatic equation 1st law of thermodynamics moisture parameters adiabatic / pseudoadiabatic processes stability criteria / cloud formation Microphysics of warm clouds nucleation of water vapor by condensation growth of cloud droplets in warm clouds (condensation, fall speed of droplets, collection, coalescence) formation of rain, stochastical coalescence Microphysics of cold clouds homogeneous, heterogeneous, and contact nucleation concentration of ice particles in clouds crystal growth (from vapor phase, riming, aggregation) formation of precipitation, cloud modification Observation of cloud microphysical properties Parameterization of clouds in climate and NWP models Cloud microphysics December 15, 2011 2 / 30 Growth Precipitation Cloud modification Growth from the vapor phase in mixed-phase clouds mixed-phase cloud is dominated by super-cooled droplets air is close to saturated w.r.t. liquid water air is supersaturated w.r.t. ice Example ◦ T=-10 C, RHl ≈ 100%, RHi ≈ 110% ◦ T=-20 C, RHl ≈ 100%, RHi ≈ 121% )much greater supersaturations than in warm clouds In mixed-phase clouds, ice particles grow from vapor phase much more rapidly than droplets. Cloud microphysics December 15, 2011 3 / 30 Growth Precipitation Cloud modification Mass growth rate of an ice crystal diffusional growth of ice crystal similar to growth of droplet by condensation more complicated, mainly because ice crystals are not spherical )points of equal water vapor do not lie on a sphere centered on crystal dM = 4πCD (ρ (1) − ρ ) dt v vc Cloud microphysics December 15, 2011 4 / 30 P732951-Ch06.qxd 9/12/05 7:44 PM Page 240 240 Cloud Microphysics determined by the size and shape of the conductor.