The International Classification for Seasonal Snow on the Ground
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PRECIPITATION What Does a 60 Percent Chance of Precipitation Mean?
PRECIPITATION What does a 60 percent chance of precipitation mean? http://www.cbc.ca/news/canada/ottawa/canada-weather-forecast-no-50-per-cent-forecast-1.4206067 The probability of (PoP) does not mean • the percent of time precipitation will be observed over the area; or • the percentage of meteorologists who believe precipitation will fall! The most common definition among meteorologists is the probability that at least one one-hundredth inch of liquid-equivalent precipitation will fall in a single spot. Here’s a good way to grasp a PoP of 60 percent: If we had ten tomorrows with identical weather conditions, any given point would receive rain on six (60 percent) of those days. And rain would not fall on four of those days — on any given point. Remember: this PoP is a forecast for 10 potential tomorrows, not a forecast for the next 10 days! Although this may be confusing, weather forecasters have no problem thinking of tomorrow’s weather as a group of potential tomorrows. One thing you can take to the bank: as the PoP increases, precipitation grows more likely. In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravity. So many types… Rain Sleet Drizzle Hail Snow Graupel Thundersnow Fog and mist are technically SUSPENSIONS and not precipitation SYMBOLS RAINSHOWERS are identified on weather maps as a dot over a triangle Heavier rain as a series of dots, more when rain is heavier Rain - and other forms of precipitation - occur when Basically… warm moist air cools and condensation occurs. -
Ice Ic” Werner F
Extent and relevance of stacking disorder in “ice Ic” Werner F. Kuhsa,1, Christian Sippela,b, Andrzej Falentya, and Thomas C. Hansenb aGeoZentrumGöttingen Abteilung Kristallographie (GZG Abt. Kristallographie), Universität Göttingen, 37077 Göttingen, Germany; and bInstitut Laue-Langevin, 38000 Grenoble, France Edited by Russell J. Hemley, Carnegie Institution of Washington, Washington, DC, and approved November 15, 2012 (received for review June 16, 2012) “ ” “ ” A solid water phase commonly known as cubic ice or ice Ic is perfectly cubic ice Ic, as manifested in the diffraction pattern, in frequently encountered in various transitions between the solid, terms of stacking faults. Other authors took up the idea and liquid, and gaseous phases of the water substance. It may form, attempted to quantify the stacking disorder (7, 8). The most e.g., by water freezing or vapor deposition in the Earth’s atmo- general approach to stacking disorder so far has been proposed by sphere or in extraterrestrial environments, and plays a central role Hansen et al. (9, 10), who defined hexagonal (H) and cubic in various cryopreservation techniques; its formation is observed stacking (K) and considered interactions beyond next-nearest over a wide temperature range from about 120 K up to the melt- H-orK sequences. We shall discuss which interaction range ing point of ice. There was multiple and compelling evidence in the needs to be considered for a proper description of the various past that this phase is not truly cubic but composed of disordered forms of “ice Ic” encountered. cubic and hexagonal stacking sequences. The complexity of the König identified what he called cubic ice 70 y ago (11) by stacking disorder, however, appears to have been largely over- condensing water vapor to a cold support in the electron mi- looked in most of the literature. -
Analysis of Thundersnow Storms Over Northern Colorado
DECEMBER 2015 K U M J I A N A N D D E I E R L I N G 1469 Analysis of Thundersnow Storms over Northern Colorado MATTHEW R. KUMJIAN Department of Meteorology, The Pennsylvania State University, University Park, Pennsylvania WIEBKE DEIERLING Research Applications Laboratory, National Center for Atmospheric Research,* Boulder, Colorado (Manuscript received 13 January 2015, in final form 12 August 2015) ABSTRACT Lightning flashes during snowstorms occur infrequently compared to warm-season convection. The rarity of such thundersnow events poses an additional hazard because the lightning is unexpected. Because cloud electrification in thundersnow storms leads to relatively few lightning discharges, studying thundersnow events may offer insights into mechanisms for charging and possible thresholds required for lightning dis- charges. Observations of four northern Colorado thundersnow events that occurred during the 2012/13 winter are presented. Four thundersnow events in one season strongly disagrees with previous climatologies that used surface reports, implying thundersnow may be more common than previously thought. Total lightning information from the Colorado Lightning Mapping Array and data from conterminous United States light- ning detection networks are examined to investigate the snowstorms’ electrical properties and to compare them to typical warm-season thunderstorms. Data from polarimetric WSR-88Ds near Denver, Colorado, and Cheyenne, Wyoming, are used to reveal the storms’ microphysical structure and determine operationally relevant signatures related to storm electrification. Most lightning occurred within convective cells containing graupel and pristine ice. However, one flash occurred in a stratiform snowband, apparently triggered by a tower. Depolarization streaks were observed in the radar data prior to the flash, indicating electric fields strong enough to orient pristine ice crystals. -
Calving Processes and the Dynamics of Calving Glaciers ⁎ Douglas I
Earth-Science Reviews 82 (2007) 143–179 www.elsevier.com/locate/earscirev Calving processes and the dynamics of calving glaciers ⁎ Douglas I. Benn a,b, , Charles R. Warren a, Ruth H. Mottram a a School of Geography and Geosciences, University of St Andrews, KY16 9AL, UK b The University Centre in Svalbard, PO Box 156, N-9171 Longyearbyen, Norway Received 26 October 2006; accepted 13 February 2007 Available online 27 February 2007 Abstract Calving of icebergs is an important component of mass loss from the polar ice sheets and glaciers in many parts of the world. Calving rates can increase dramatically in response to increases in velocity and/or retreat of the glacier margin, with important implications for sea level change. Despite their importance, calving and related dynamic processes are poorly represented in the current generation of ice sheet models. This is largely because understanding the ‘calving problem’ involves several other long-standing problems in glaciology, combined with the difficulties and dangers of field data collection. In this paper, we systematically review different aspects of the calving problem, and outline a new framework for representing calving processes in ice sheet models. We define a hierarchy of calving processes, to distinguish those that exert a fundamental control on the position of the ice margin from more localised processes responsible for individual calving events. The first-order control on calving is the strain rate arising from spatial variations in velocity (particularly sliding speed), which determines the location and depth of surface crevasses. Superimposed on this first-order process are second-order processes that can further erode the ice margin. -
Ice Flow Impacts the Firn Structure of Greenland's Percolation Zone
University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 2019 Ice Flow Impacts the Firn Structure of Greenland's Percolation Zone Rosemary C. Leone University of Montana, Missoula Follow this and additional works at: https://scholarworks.umt.edu/etd Part of the Glaciology Commons Let us know how access to this document benefits ou.y Recommended Citation Leone, Rosemary C., "Ice Flow Impacts the Firn Structure of Greenland's Percolation Zone" (2019). Graduate Student Theses, Dissertations, & Professional Papers. 11474. https://scholarworks.umt.edu/etd/11474 This Thesis is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. ICE FLOW IMPACTS THE FIRN STRUCTURE OF GREENLAND’S PERCOLATION ZONE By ROSEMARY CLAIRE LEONE Bachelor of Science, Colorado School of Mines, Golden, CO, 2015 Thesis presented in partial fulfillMent of the requireMents for the degree of Master of Science in Geosciences The University of Montana Missoula, MT DeceMber 2019 Approved by: Scott Whittenburg, Dean of The Graduate School Graduate School Dr. Joel T. Harper, Chair DepartMent of Geosciences Dr. Toby W. Meierbachtol DepartMent of Geosciences Dr. Jesse V. Johnson DepartMent of Computer Science i Leone, RoseMary, M.S, Fall 2019 Geosciences Ice Flow Impacts the Firn Structure of Greenland’s Percolation Zone Chairperson: Dr. Joel T. Harper One diMensional siMulations of firn evolution neglect horizontal transport as the firn column Moves down slope during burial. -
Comparison of Remote Sensing Extraction Methods for Glacier Firn Line- Considering Urumqi Glacier No.1 As the Experimental Area
E3S Web of Conferences 218, 04024 (2020) https://doi.org/10.1051/e3sconf/202021804024 ISEESE 2020 Comparison of remote sensing extraction methods for glacier firn line- considering Urumqi Glacier No.1 as the experimental area YANJUN ZHAO1, JUN ZHAO1, XIAOYING YUE2and YANQIANG WANG1 1College of Geography and Environmental Science, Northwest Normal University, Lanzhou, China 2State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources/Tien Shan Glaciological Station, Chinese Academy of Sciences, Lanzhou, China Abstract. In mid-latitude glaciers, the altitude of the snowline at the end of the ablating season can be used to indicate the equilibrium line, which can be used as an approximation for it. In this paper, Urumqi Glacier No.1 was selected as the experimental area while Landsat TM/ETM+/OLI images were used to analyze and compare the accuracy as well as applicability of the visual interpretation, Normalized Difference Snow Index, single-band threshold and albedo remote sensing inversion methods for the extraction of the firn lines. The results show that the visual interpretation and the albedo remote sensing inversion methods have strong adaptability, alonger with the high accuracy of the extracted firn line while it is followed by the Normalized Difference Snow Index and the single-band threshold methods. In the year with extremely negative mass balance, the altitude deviation of the firn line extracted by different methods is increased. Except for the years with extremely negative mass balance, the altitude of the firn line at the end of the ablating season has a good indication for the altitude of the balance line. -
Glacier (And Ice Sheet) Mass Balance
Glacier (and ice sheet) Mass Balance The long-term average position of the highest (late summer) firn line ! is termed the Equilibrium Line Altitude (ELA) Firn is old snow How an ice sheet works (roughly): Accumulation zone ablation zone ice land ocean • Net accumulation creates surface slope Why is the NH insolation important for global ice• sheetSurface advance slope causes (Milankovitch ice to flow towards theory)? edges • Accumulation (and mass flow) is balanced by ablation and/or calving Why focus on summertime? Ice sheets are very sensitive to Normal summertime temperatures! • Ice sheet has parabolic shape. • line represents melt zone • small warming increases melt zone (horizontal area) a lot because of shape! Slightly warmer Influence of shape Warmer climate freezing line Normal freezing line ground Furthermore temperature has a powerful influence on melting rate Temperature and Ice Mass Balance Summer Temperature main factor determining ice growth e.g., a warming will Expand ablation area, lengthen melt season, increase the melt rate, and increase proportion of precip falling as rain It may also bring more precip to the region Since ablation rate increases rapidly with increasing temperature – Summer melting controls ice sheet fate* – Orbital timescales - Summer insolation must control ice sheet growth *Not true for Antarctica in near term though, where it ʼs too cold to melt much at surface Temperature and Ice Mass Balance Rule of thumb is that 1C warming causes an additional 1m of melt (see slope of ablation curve at right) -
US Marine Corps MWTC Cold Weather
UNITED STATES MARINE CORPS Mountain Warfare Training Center Bridgeport, California 93517-5001 COLD WEATHER MEDICINE COURSE TABLE OF CONTENTS CHAP TITLE 1 MOUNTAIN SAFETY (WINTER) 2 SURVIVAL KIT 3 COLD WEATHER CLOTHING 4 WINTER WARFIGHTING LOAD REQUIREMENTS 5 NOMENCLATURE AND CARE OF MILITARY SKI EQUIPMENT 6 MILITARY SNOWSHOE MOVEMENT 7 PREVENTIVE MEDICINE 8 PATIENT ASSESSMENT 9 TRIAGE 10 TACTICAL COMBAT CASUALTY CARE 11 LAND NAVIGATION REVIEW 12 NUTRITION 13 HYPOTHERMIA 14 FREEZING / NEAR FREEZING TISSUE INJURIES 15 EXTREME COLD WEATHER TENT 16 PERSONAL / TEAM STOVES 17 TEN MAN ARCTIC TENT 18 BURN MANAGEMENT 19 MISCELLANEOUS COLD WEATHER MEDICAL PROBLEMS 20 CASEVACS AND CASEVAC REPORTING 21 HIGH ALTITUDE HEALTH PROBLEMS 22 ENVIRONMENTAL HAZARDS 1 23 ENVIRONMENTAL HAZARDS 2 24 AVALANCHE SEARCH ORGANIZATION 25 AVALANCHE TRANSCEIVERS 26 BIVOUAC ROUTINE 27 WILDERNESS ORTHOPEDIC TRAUMA 28 COLD WEATHER LEADERSHIP PROBLEMS 29 SUBMERSION INCIDENTS 30 REQUIREMENTS FOR SURVIVAL 31 SURVIVAL SIGNALING 32 SURVIVAL SNOW SHELTERS AND FIRES 33 SKIJORING UNITED STATES MARINE CORPS Mountain Warfare Training Center Bridgeport, California 93517-5001 FMST.07.18 10/22/01 STUDENT HANDOUT MOUNTAIN SAFETY (WINTER) TERMINAL LEARNING OBJECTIVE. Given a unit in a wilderness environment and necessary equipment and supplies, apply the principles of mountain safety, to prevent death or injury per the references. (FMST.07.18) ENABLING LEARNING OBJECTIVE. 1. Without the aid of references, and given the acronym "BE SAFE MARINE", list in writing the 12 principles of mountain safety, in accordance with the references. (FMST.07.18a) OUTLINE. 1. P LANNING AND PREPARATION. (FMST.07.18a) As in any military operation, planning and preparation constitute the keys to success. -
A Field Guide to Falling Snow
Basic Snowflake Forms (from SnowCrystals.com) Although no two snowflakes are exactly alike, snow crystal forms usually fall into several broad categories. You can find a more descriptive guide in the book – The Snowflake: Winter’s Secret Beauty. Stellar Dendrites Dendrite means "tree-like", which describes the multi-branched appearance of these snow crystals. Stellar dendrites have six symmetrical main branches and a large number of randomly placed sidebranches. They can also be large, perhaps 5mm in diameter. Although they have complex shapes, each stellar dendrite is a single crystal of ice. The molecular ordering of the water molecules is the same from one side of the crystal to the other. Sectored Plates What identifies these crystals are the numerous ice ridges that seem to divide the plate-like arms into sectors -- hence the name. Like the stellar dendrites, sectored plates are flat, thin slivers of ice that grow into in a stunning diversity of complex shapes. Hollow Columns Plate-like snow crystals get the most attention, but columnar crystals are the main constituents of many snowfalls. The columns are hexagonal, like a wooden pencil, and they often form with conical hollow features in their ends. Needles Columnar crystals can grow so long and thin that they look like ice needles. Sometimes the needles contain thin hollow regions, and sometimes the ends split into additional needle branches. Spatial Dendrites Not all snowflakes form as thin flat plates or slender columns. Spatial dendrites are made from many individual ice crystals jumbled together. Each branch is like one arm of a stellar crystal, but the different branches are oriented randomly. -
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. -
Properties of Diamond Dust Type Ice Crystals Observed in Summer Season at Amundsen-Scott South Pole Station, Antarctica
180 JournaloftheMeteorological SocietyofJapanVol 57,No.2 Properties of Diamond Dust Type Ice Crystals Observed in Summer Season at Amundsen-Scott South Pole Station, Antarctica By Katsuhiro Kikuchi Department of Geophysics, Hokkaido University, Sapporo and Austin W. Hogan Atmospheric Sciences Research Center, State University of New York at Albany, Albany, New York (Manuscript received 17 November 1977, in revised form 20 May 1978) Abstract The properties of diamond dust type ice crystals were studied from replicas obtained during the 1975 austral summer at South Pole Station, Antarctica. The time variation of the number concentration and shapes of crystals, and the length of the c-axis, the axial ratio (c/a) and the growth mode of columnar type crystal were examined at an air tempera- ture of -35*. Columnar type crystals prevailed, but occasionally more than half the number of ice crystals were plate types, including hexagonal, scalene hexagonal, pentagonal, rhombic, trapezoidal and triangular plates. A time variation of two hour periodicity was found in the number concentration of columnar and plate type crystals. When the number con- centration of columnar type crystals decreased, the length of the c-axis of columnar type crystals also decreased. When the number concentration of columnar type crystals increased, the length of the c-axis of the crystals also increased. There was sufficient water vapor to grow these ice crystals in a supersaturation layer several tens to several hundred meters above the surface. The growth mode of columnar type crystals was different from that of warm and cold region columns reported by Ono (1969). The mass growth rate was 6.0* 10-10 gr*sec-1, and was similar to that obtained in cold room experiments by Mason (1953), but less than that found in field experiments by Isono, et al. -
Dear Editor and Reviewers
Dear Editor and Reviewers, We are grateful for your constructive review of our manuscript. We made our best to address all the suggestions and provide an improved and fully revised manuscript. A response to each of the reviewers’ comments is given below but we would like to highlight the most important updates of manuscript: - We now present a research article with improved visuals and more in-depth discussion. - We compare our FAC dataset and maps to three regional climate models. - The construction of empirical functions is slightly updated, simplified and presented in the main text. We thank the reviewers for improving significantly the study. Sincerely, Baptiste Vandecrux on behalf of the co-authors Review #1 by Sergey Marchenko Reviewer’s comment Authors’ response General comments Physical geography. Authors use the mean annual air temperature and net surface accumulation as arguments in functions describing the spatial distribution of FAC10. The functions are fitted to minimize the misfit with empirical estimates of FAC10 from cores. One important thing that is missing in the text is a detailed description of the physical (or may be practical) motivation for the choice of the above mentioned arguments. Both characteristics (net annual surface accumulation and mean annual air temperature) integrate the effects of processes occurring during the cold and warm parts of a year. Net annual surface accumulation is the result of mass accumulation in winter and surface melt in In our study 풃̅̇ is defined as “net snow summer. While the first one can be expected to be positively linked with FAC (more accumulation in accumulation” (snowfall + deposition – sublimation) and is not “Net annual surface winter -> more pores), the second one can be expected to be negatively linked with FAC (more melt accumulation”.