DOCSLIB.ORG

Weather Forecasting Models, Methods and Applications AA Iseh

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Weather Forecasting Models, Methods and Applications AA Iseh International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 2 Issue 12, December - 2013 Weather Forecasting Models, Methods and Applications AA Iseh. A. J.1* Woma. T. Y.1,2 1. Department of Pure & Applied Physics, Federal University Wukari, Taraba State. P. M. B. 1020 Wukari, Taraba State. 2. Department of Pure & Applied Physics, Federal University Wukari, Taraba State. P. M. B. 1020 Wukari, Taraba State. ABSTRACT weather data, forecasting methods and Weather forecasting modelling is a applications. computer program that provides meteorological information for future 1.0 INTRODUCTION times at given locations. In modern forecasting models, Numerical Weather Prediction is mostly applied and this Modern society’s ever-increasing demand means, “a set of simplified equations used for more accurate weather forecasts is to calculate changes in atmospheric evident to most people. The spectrum of conditions”. The act of writing these needs for weather predictions ranges from equations, imposing the boundary the general public’s desire to know if for conditions and solving them using super instance, the weekend will permit an computers, is known as numerical outing at the beach, or an organization’s modelling. An example of such equations rally, or an outdoor wedding reception. Such diverse industries as airlines and fruit is the Hypsometric equation given as PI = growers depend heavily on accurate POexp–gz/RT. Computerized numerical models are designed for different intervals weather forecasts to have an idea of what which are known as global models underIJERT IJERTtheir next schedule of flight would appear which we have long range forecast and to be or if the weather will be suitable for medium range forecast, and regional harvesting. In addition, in developed models under which we have the short countries, the designs of buildings, and range forecast. The methods include many industrial facilities rely heavily on a persistence, climatologic, looking at the sound knowledge of the atmosphere. sky, use of barometer, nowcasting, use of Weather forecasting can be defined as the forecasting models, analogue and act of predicting future weather conditions ensemble forecasting. Forecasting could be or an attempt to indicate the weather applied in air traffic, severe weather alerts, conditions which are likely to occur. marine, agriculture, utility companies, private sector and military application. Weather forecasting is the application of Weather forecasting is a complex and Science and Technology to predict the challenging science that depends on the state of the atmosphere for a future time efficient interplay of weather observation, and a given location. Human beings have data analysis by meteorologist and attempted to predict the weather computers, and rapid communication informally for millennia, and formally system. since at least the nineteenth century. Weather forecasts are made by collecting Key words: Weather, weather qualitative data about the current state of prediction, forecast, forecasting models, the atmosphere and using scientific understanding of atmospheric processes to IJERTV2IS120198 www.ijert.org 1945 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 2 Issue 12, December - 2013 project how the atmosphere will evolve 2.0 HOW MODELS CREATE within the next few hours. FORECASTS Once, an all-human endeavour based mainly upon changes in barometric 2.1 Data collection pressure, current weather conditions and Since invention of the first weather sky conditions, forecast models are now instruments in the seventeenth century used to determine future conditions. A weather observation has undergone model, in this context, is a computer considerable refinement. Denser program that produces meteorological monitoring networks, more sophisticated information for future times at given instruments and communication systems, positions and altitudes. The horizontal and better-trained weather observers, have domain of a model is either global, produced an increasingly detailed, reliable covering the entire earth, or regional, and representative record of weather and covering only part of the earth. Regional climate. In weather forecasting, data models also are known as limited area collection has been divided into two models. Human input is still required to categories namely: pick the best possible forecast model to i. Surface weather observations base the forecast upon, which involves ii. Upper-air weather observations. pattern recognition skills, knowledge of model performance and knowledge of model biases. The chaotic nature of the Surface Weather Observations atmosphere, error involved in measuring Surface weather observations are the the initial conditions, an incomplete fundamental data used for safety as well as understanding of atmospheric processes climatological reasons to forecast weather mean that forecast become less accurate as and issue warnings worldwide. They can the difference in current time and the time be taken manually by a weather observer, for which the forecast is being made by computer through observers to augment increases. IJERTIJERTthe otherwise automated weather station. There are a variety of end users to weather Referring to Lutgens and TarBuck (1989), forecasts. Weather warnings are important a vast network of weather stations required forecasts because they are used to protect to produce a weather chart will encompass life and property. Forecasts based on enough to be useful for short-range temperature and precipitation are forecasts. On a global scale, the World important to agriculture, and therefore to meteorological organization, which commodity traders within stock markets. consists of over 130 nations, is responsible Temperature forecasts are also used by for gathering the needed data and utility companies to estimate demand over producing some general prognostic charts. coming days. On an everyday basis people use weather forecasts to determine what to Surface weather observations of wear on a given day. Since in recent time atmospheric pressure, temperature, wind in Uyo – Nigeria for example, outdoor speed and direction, humidity, activities are severely curtailed by heavy precipitations are made near the earth’s rains, forecasts can be used to plan surface by trained observers or automatic activities around these events, and to plan weather stations. The World ahead and survive them. meteorological Organization acts to standardize the instrumentation, observing practices and timing of those observations worldwide. By international agreement, the regular synoptic observations are made every six hours beginning at midnight IJERTV2IS120198 www.ijert.org 1946 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 Vol. 2 Issue 12, December - 2013 Greenwish Mean Time (0000GMT, of points where there are processed by a 0600GMT, 1200GMT and 1800GMT) Central weather analysis organization. each day. In addition, observations for Three locations have been designated by aviation purposes are made at many the World Meteorological Organization as airports every hour, or more often if the World Meteorological Centers, these are weather is changing rapidly. Specialized located in Melbourne, Australia; Moscow, observations may also be made under Russia; and Washington, D.C. U.S.A. In certain conditions for agricultural, addition, most countries maintain national industrial, research, or other purposes centers, where the basic weather needs of (Miller and Thompson, 1975). the domestic economy are met. In Nigeria, the National Meteorological Center is located in Abuja. Upper-air weather observations Measurements of temperature, humidity 2.1.1 Data assimilation and and wind above the surface are found by analysis launching radiosondes on weather In order to do their work, most numerical balloons. Radiosonde is a unit for use in models look at the atmosphere as a series weather balloons that measures various of boxes. In the middle of each box is a atmospheric parameters and transits them point for which the model actually to a fixed receiver. Radiosondes may calculates weather variables and makes operate at a radio frequency of 403MHz or forecasts. The result of this three 1680MHz and both types may be adjusted dimensional boxing up of the atmosphere slightly higher or lower as required. is known as the grid; the point in the Mohan and Morgan (1991) states that, the middle is the grid point, and the distance instrument transmits to the ground station between one point and another is called the vertical profiles of air temperature, grid spacing (Ackerman and Knox, 2003). pressure, and relative humidity up to an altitude of about 30km. In addition, winds Grid point models of the atmosphere can at various levels are computed by trackingIJERT IJERTget fussy when the data in the initial the balloons with a radio direction finding conditions is not obtained at exactly the antenna. location of the grid point. Also, the process of creating an evenly spaced data set from Upper-air weather data are also obtained irregularly spaced observations is called by aircraft, dropwind sondes, radar, and interpolation. satellites. Increasingly, data from weather satellites are being used because of their Ackerman and Knox (2003) then say that, almost global coverage. Although their the multiple jobs of interpolating and visible light images are very useful for smoothing the data for use in numerical forecasters to see development of clouds,
Load more

Recommended publications
  • Comparing Historical and Modern Methods of Sea Surface Temperature
    EGU Journal Logos (RGB) Open Access Open Access Open Access Advances in Annales Nonlinear Processes Geosciences Geophysicae in Geophysics Open Access Open Access Natural Hazards Natural Hazards and Earth System and Earth System Sciences Sciences Discussions Open Access Open Access Atmospheric Atmospheric Chemistry Chemistry and Physics and Physics Discussions Open Access Open Access Atmospheric Atmospheric Measurement Measurement Techniques Techniques Discussions Open Access Open Access Biogeosciences Biogeosciences Discussions Open Access Open Access Climate Climate of the Past of the Past Discussions Open Access Open Access Earth System Earth System Dynamics Dynamics Discussions Open Access Geoscientific Geoscientific Open Access Instrumentation Instrumentation Methods and Methods and Data Systems Data Systems Discussions Open Access Open Access Geoscientific Geoscientific Model Development Model Development Discussions Open Access Open Access Hydrology and Hydrology and Earth System Earth System Sciences Sciences Discussions Open Access Ocean Sci., 9, 683–694, 2013 Open Access www.ocean-sci.net/9/683/2013/ Ocean Science doi:10.5194/os-9-683-2013 Ocean Science Discussions © Author(s) 2013. CC Attribution 3.0 License. Open Access Open Access Solid Earth Solid Earth Discussions Comparing historical and modern methods of sea surface Open Access Open Access The Cryosphere The Cryosphere temperature measurement – Part 1: Review of methods, Discussions field comparisons and dataset adjustments J. B. R. Matthews School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada Correspondence to: J. B. R. Matthews ([email protected]) Received: 3 August 2012 – Published in Ocean Sci. Discuss.: 20 September 2012 Revised: 31 May 2013 – Accepted: 12 June 2013 – Published: 30 July 2013 Abstract. Sea surface temperature (SST) has been obtained 1 Introduction from a variety of different platforms, instruments and depths over the past 150 yr.
    [Show full text]
  • Forecasting Tropical Cyclones
    Forecasting Tropical Cyclones Philippe Caroff, Sébastien Langlade, Thierry Dupont, Nicole Girardot Using ECMWF Forecasts – 4-6 june 2014 Outline . Introduction . Seasonal forecast . Monthly forecast . Medium- to short-range forecasts For each time-range we will see : the products, some elements of assessment or feedback, what is done with the products Using ECMWF Forecasts – 4-6 june 2014 RSMC La Réunion La Réunion is one of the 6 RSMC for tropical cyclone monitoring and warning. Its responsibility area is the south-west Indian Ocean. http://www.meteo.fr/temps/domtom/La_Reunion/webcmrs9.0/# Introduction Seasonal forecast Monthly forecast Medium- to short-range Other activities in La Réunion TRAINING Organisation of international training courses and workshops RESEARCH Research Centre for tropical Cyclones (collaboration with La Réunion University) LACy (Laboratoire de l’Atmosphère et des Cyclones) : https://lacy.univ-reunion.fr DEMONSTRATION SWFDP (Severe Weather Forecasting Demonstration Project) http://www.meteo.fr/extranets/page/index/affiche/id/76216 Introduction Seasonal forecast Monthly forecast Medium- to short-range Seasonal variability • The cyclone season goes from 1st of July to 30 June but more than 90% of the activity takes place between November and April • The average number of named cyclones (i.e. tropical storms) is 9. • But the number of tropical cyclones varies from year to year (from 3 to 14) Can the seasonal forecast systems give indication of this signal ? Introduction Seasonal forecast Monthly forecast Medium- to short-range Seasonal Forecast Products Forecasts of tropical cyclone activity anomaly are produced with ECMWF Seasonal Forecast System, and also with EUROSIP models (union of UKMO+ECMWF+NCEP+MF seasonal forecast systems) Other products can be informative, for example SST plots.
    [Show full text]
  • Moons Phases and Tides
    Moon’s Phases and Tides Moon Phases Half of the Moon is always lit up by the sun. As the Moon orbits the Earth, we see different parts of the lighted area. From Earth, the lit portion we see of the moon waxes (grows) and wanes (shrinks). The revolution of the Moon around the Earth makes the Moon look as if it is changing shape in the sky The Moon passes through four major shapes during a cycle that repeats itself every 29.5 days. The phases always follow one another in the same order: New moon Waxing Crescent First quarter Waxing Gibbous Full moon Waning Gibbous Third (last) Quarter Waning Crescent • IF LIT FROM THE RIGHT, IT IS WAXING OR GROWING • IF DARKENING FROM THE RIGHT, IT IS WANING (SHRINKING) Tides • The Moon's gravitational pull on the Earth cause the seas and oceans to rise and fall in an endless cycle of low and high tides. • Much of the Earth's shoreline life depends on the tides. – Crabs, starfish, mussels, barnacles, etc. – Tides caused by the Moon • The Earth's tides are caused by the gravitational pull of the Moon. • The Earth bulges slightly both toward and away from the Moon. -As the Earth rotates daily, the bulges move across the Earth. • The moon pulls strongly on the water on the side of Earth closest to the moon, causing the water to bulge. • It also pulls less strongly on Earth and on the water on the far side of Earth, which results in tides. What causes tides? • Tides are the rise and fall of ocean water.
    [Show full text]
  • Improving Lightning and Precipitation Prediction of Severe Convection Using of the Lightning Initiation Locations
    PUBLICATIONS Journal of Geophysical Research: Atmospheres RESEARCH ARTICLE Improving Lightning and Precipitation Prediction of Severe 10.1002/2017JD027340 Convection Using Lightning Data Assimilation Key Points: With NCAR WRF-RTFDDA • A lightning data assimilation method was developed Haoliang Wang1,2, Yubao Liu2, William Y. Y. Cheng2, Tianliang Zhao1, Mei Xu2, Yuewei Liu2, Si Shen2, • Demonstrate a method to retrieve the 3 3 graupel fields of convective clouds Kristin M. Calhoun , and Alexandre O. Fierro using total lightning data 1 • The lightning data assimilation Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information method improves the lightning and Science and Technology, Nanjing, China, 2National Center for Atmospheric Research, Boulder, CO, USA, 3Cooperative convective precipitation short-term Institute for Mesoscale Meteorological Studies (CIMMS), NOAA/National Severe Storms Laboratory, University of Oklahoma forecasts (OU), Norman, OK, USA Abstract In this study, a lightning data assimilation (LDA) scheme was developed and implemented in the Correspondence to: Y. Liu, National Center for Atmospheric Research Weather Research and Forecasting-Real-Time Four-Dimensional [email protected] Data Assimilation system. In this LDA method, graupel mixing ratio (qg) is retrieved from observed total lightning. To retrieve qg on model grid boxes, column-integrated graupel mass is first calculated using an Citation: observation-based linear formula between graupel mass and total lightning rate. Then the graupel mass is Wang, H., Liu, Y., Cheng, W. Y. Y., Zhao, distributed vertically according to the empirical qg vertical profiles constructed from model simulations. … T., Xu, M., Liu, Y., Fierro, A. O. (2017). Finally, a horizontal spread method is utilized to consider the existence of graupel in the adjacent regions Improving lightning and precipitation prediction of severe convection using of the lightning initiation locations.
    [Show full text]
  • Winter 2020/2021 Volume 18
    NATIONAL WEATHER SERVICE GREEN BAY Winter 2020/2021 Volume 18 Lake Michigan water levels remain near record highs BY: mike cellitti Inside this issue: In December 2012 and January 2013, the Lake Michigan-Huron basin (Lake Michigan and Lake Huron are treated as one lake from a hydrologic perspective) East River Watershed 3 Resiliency Project observed record low water levels, making it the 14th consecutive year of below normal water levels. These record low water levels garnered national attention 2020-21 Winter Forecast 4 raising concerns for the shipping industry, climate impacts, and the long-term future Ambassador of Excellence 6 of the Great Lakes water levels. Since this minimum in water levels 6 years ago, Lake Kotenberg Joins NWS 7 Michigan-Huron has been on the rise, culminating in record high water levels for much of this year (Figure 1). In fact, Lake Michigan-Huron set monthly mean record Severe Weather Spotters 7 high water levels from January to August, peaking in July at greater than 3 inches Thank You Observers! 8 above the previous record. Word Search 9 The water level on the Great Lakes can fluctuate on a monthly, seasonal, and annual basis depending upon a variety of factors including the amount of precipitation, evaporation, and rainfall induced runoff. Precipitation and runoff typically peak in late spring and summer as a result of snowmelt and thunderstorm activity. Although it is difficult to measure, evaporation occurs the most when cold air flows over the relatively warm waters of the Great Lakes during the fall and winter months. East River The record high water levels of Lake Michigan-Huron are largely a result of well Flooding above normal precipitation across the basin over the past 5 years.
    [Show full text]
  • Wind Energy Forecasting: a Collaboration of the National Center for Atmospheric Research (NCAR) and Xcel Energy
    Wind Energy Forecasting: A Collaboration of the National Center for Atmospheric Research (NCAR) and Xcel Energy Keith Parks Xcel Energy Denver, Colorado Yih-Huei Wan National Renewable Energy Laboratory Golden, Colorado Gerry Wiener and Yubao Liu University Corporation for Atmospheric Research (UCAR) Boulder, Colorado NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. S ubcontract Report NREL/SR-5500-52233 October 2011 Contract No. DE-AC36-08GO28308 Wind Energy Forecasting: A Collaboration of the National Center for Atmospheric Research (NCAR) and Xcel Energy Keith Parks Xcel Energy Denver, Colorado Yih-Huei Wan National Renewable Energy Laboratory Golden, Colorado Gerry Wiener and Yubao Liu University Corporation for Atmospheric Research (UCAR) Boulder, Colorado NREL Technical Monitor: Erik Ela Prepared under Subcontract No. AFW-0-99427-01 NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. National Renewable Energy Laboratory Subcontract Report 1617 Cole Boulevard NREL/SR-5500-52233 Golden, Colorado 80401 October 2011 303-275-3000 • www.nrel.gov Contract No. DE-AC36-08GO28308 This publication received minimal editorial review at NREL. NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.
    [Show full text]
  • The Error Is the Feature: How to Forecast Lightning Using a Model Prediction Error [Applied Data Science Track, Category Evidential]
    The Error is the Feature: How to Forecast Lightning using a Model Prediction Error [Applied Data Science Track, Category Evidential] Christian Schön Jens Dittrich Richard Müller Saarland Informatics Campus Saarland Informatics Campus German Meteorological Service Big Data Analytics Group Big Data Analytics Group Offenbach, Germany ABSTRACT ACM Reference Format: Despite the progress within the last decades, weather forecasting Christian Schön, Jens Dittrich, and Richard Müller. 2019. The Error is the is still a challenging and computationally expensive task. Current Feature: How to Forecast Lightning using a Model Prediction Error: [Ap- plied Data Science Track, Category Evidential]. In Proceedings of 25th ACM satellite-based approaches to predict thunderstorms are usually SIGKDD Conference on Knowledge Discovery and Data Mining (KDD ’19). based on the analysis of the observed brightness temperatures in ACM, New York, NY, USA, 10 pages. different spectral channels and emit a warning if a critical threshold is reached. Recent progress in data science however demonstrates 1 INTRODUCTION that machine learning can be successfully applied to many research fields in science, especially in areas dealing with large datasets. Weather forecasting is a very complex and challenging task requir- We therefore present a new approach to the problem of predicting ing extremely complex models running on large supercomputers. thunderstorms based on machine learning. The core idea of our Besides delivering forecasts for variables such as the temperature, work is to use the error of two-dimensional optical flow algorithms one key task for meteorological services is the detection and pre- applied to images of meteorological satellites as a feature for ma- diction of severe weather conditions.
    [Show full text]
  • USING a LIGHTNING SAFETY TOOLKIT for OUTDOOR VENUES Charles C
    USING A LIGHTNING SAFETY TOOLKIT FOR OUTDOOR VENUES Charles C. Woodrum Meteorologist National Weather Service, NOAA Pittsburgh, Pennsylvania Donna Franklin Office of Climate, Water, and Weather Services National Weather Service, NOAA Silver Spring, Maryland _________________________ Abstract guidelines that are used as a template for creating a new plan or enhancing an existing plan. The toolkit The threat of fatal lightning strikes at outdoor was developed within the framework of NCAA venues continues to be a pressing concern for event Guideline 1d. The NWS used plans from the managers. Several delays were documented in 2010 University of Tampa, the University of Maryland, and and 2011 in which spectators did not have enough time Vanderbilt University along with guidance from to evacuate, or chose to wait out delays in unsafe emergency management at the University of locations. To address this issue, the National Weather Tennessee and Florida State University as assistance Service (NWS) developed a lightning safety toolkit and to develop the toolkit. recognition program to help meteorologists work with venue officials to encourage sound and proactive Guidelines established for venue decisions when thunderstorms threaten their venue. management include: redundant data reception sources; effective decision support standards; 1. Introduction and Background multiple effective communication methods; a public notification plan; protection program with shelters; and Every year, hundreds of outdoor venue education of staff and patrons. The toolkit template managers are challenged to determine when an event safety plan helps venues meet these guidelines by delay is necessary due to thunderstorm hazards. In providing steps to follow before, during, and after the 2000, “ninety-two percent of National Collegiate Athletic event.
    [Show full text]
  • Multi-Sensor Improved Sea Surface Temperature (MISST) for GODAE
    Multi-sensor Improved Sea Surface Temperature (MISST) for GODAE Lead PI : Chelle L. Gentemann 438 First St, Suite 200; Santa Rosa, CA 95401-5288 Phone: (707) 545-2904x14 FAX: (707) 545-2906 E-mail: [email protected] CO-PI: Gary A. Wick NOAA/ETL R/ET6, 325 Broadway, Boulder, CO 80305 Phone: (303) 497-6322 FAX: (303) 497-6181 E-mail: [email protected] CO-PI: James Cummings Oceanography Division, Code 7320, Naval Research Laboratory, Monterey, CA 93943 Phone: (831) 656-5021 FAX: (831) 656-4769 E-mail: [email protected] CO-PI: Eric Bayler NOAA/NESDIS/ORA/ORAD, Room 601, 5200 Auth Road, Camp Springs, MD 20746 Phone: (301) 763-8102x102 FAX: ( 301) 763-8572 E-mail: [email protected] Award Number: NNG04GM56G http://www.ghrsst-pp.org http://www.usgodae.org LONG-TERM GOALS The Multi-sensor Improved Sea Surface Temperatures (MISST) for the Global Ocean Data Assimilation Experiment (GODAE) project intends to produce an improved, high-resolution, global, near-real-time (NRT), sea surface temperature analysis through the combination of satellite observations from complementary infrared (IR) and microwave (MW) sensors and to then demonstrate the impact of these improved sea surface temperatures (SSTs) on operational ocean models, numerical weather prediction, and tropical cyclone intensity forecasting. SST is one of the most important variables related to the global ocean-atmosphere system. It is a key indicator for climate change and is widely applied to studies of upper ocean processes, to air-sea heat exchange, and as a boundary condition for numerical weather prediction. The importance of SST to accurate weather forecasting of both severe events and daily weather has been increasingly recognized over the past several years.
    [Show full text]
  • CALIFORNIA STATE UNIVERSITY, NORTHRIDGE FORECASTING CALIFORNIA THUNDERSTORMS a Thesis Submitted in Partial Fulfillment of the Re
    CALIFORNIA STATE UNIVERSITY, NORTHRIDGE FORECASTING CALIFORNIA THUNDERSTORMS A thesis submitted in partial fulfillment of the requirements For the degree of Master of Arts in Geography By Ilya Neyman May 2013 The thesis of Ilya Neyman is approved: _______________________ _________________ Dr. Steve LaDochy Date _______________________ _________________ Dr. Ron Davidson Date _______________________ _________________ Dr. James Hayes, Chair Date California State University, Northridge ii TABLE OF CONTENTS SIGNATURE PAGE ii ABSTRACT iv INTRODUCTION 1 THESIS STATEMENT 12 IMPORTANT TERMS AND DEFINITIONS 13 LITERATURE REVIEW 17 APPROACH AND METHODOLOGY 24 TRADITIONALLY RECOGNIZED TORNADIC PARAMETERS 28 CASE STUDY 1: SEPTEMBER 10, 2011 33 CASE STUDY 2: JULY 29, 2003 48 CASE STUDY 3: JANUARY 19, 2010 62 CASE STUDY 4: MAY 22, 2008 91 CONCLUSIONS 111 REFERENCES 116 iii ABSTRACT FORECASTING CALIFORNIA THUNDERSTORMS By Ilya Neyman Master of Arts in Geography Thunderstorms are a significant forecasting concern for southern California. Even though convection across this region is less frequent than in many other parts of the country significant thunderstorm events and occasional severe weather does occur. It has been found that a further challenge in convective forecasting across southern California is due to the variety of sub-regions that exist including coastal plains, inland valleys, mountains and deserts, each of which is associated with different weather conditions and sometimes drastically different convective parameters. In this paper four recent thunderstorm case studies were conducted, with each one representative of a different category of seasonal and synoptic patterns that are known to affect southern California. In addition to supporting points made in prior literature there were numerous new and unique findings that were discovered during the scope of this research and these are discussed as they are investigated in their respective case study as applicable.
    [Show full text]
  • Light, Color, and Atmospheric Optics
    Light, Color, and Atmospheric Optics GEOL 1350: Introduction To Meteorology 1 2 • During the scattering process, no energy is gained or lost, and therefore, no temperature changes occur. • Scattering depends on the size of objects, in particular on the ratio of object’s diameter vs wavelength: 1. Rayleigh scattering (D/ < 0.03) 2. Mie scattering (0.03 ≤ D/ < 32) 3. Geometric scattering (D/ ≥ 32) 3 4 • Gas scattering: redirection of radiation by a gas molecule without a net transfer of energy of the molecules • Rayleigh scattering: absorption extinction 4 coefficient s depends on 1/ . • Molecules scatter short (blue) wavelengths preferentially over long (red) wavelengths. • The longer pathway of light through the atmosphere the more shorter wavelengths are scattered. 5 • As sunlight enters the atmosphere, the shorter visible wavelengths of violet, blue and green are scattered more by atmospheric gases than are the longer wavelengths of yellow, orange, and especially red. • The scattered waves of violet, blue, and green strike the eye from all directions. • Because our eyes are more sensitive to blue light, these waves, viewed together, produce the sensation of blue coming from all around us. 6 • Rayleigh Scattering • The selective scattering of blue light by air molecules and very small particles can make distant mountains appear blue. The blue ridge mountains in Virginia. 7 • When small particles, such as fine dust and salt, become suspended in the atmosphere, the color of the sky begins to change from blue to milky white. • These particles are large enough to scatter all wavelengths of visible light fairly evenly in all directions.
    [Show full text]
  • 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.
    [Show full text]