Glossary of Weather Terms
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
A Comparison of Precipitation from Maritime and Continental Air
254 BULLETIN AMERICAN METEOROLOGICAL SOCIETY A Comparison of Precipitation from Maritime and Continental Air GEORGE S. BENTON 1 and ROBERT T. BLACKBURN 2 OR many decades, knowledge of atmospheric These 123 periods of precipitation for 1946 were F movements of water vapor has lagged behind grouped as indicated below. Classifications for other phases of meteorological information. In which precipitation was necessarily from maritime recent years, however, the accumulation of upper- air are marked with an asterisk; classifications for air data has stimulated hydrometeorological re- which precipitation was necessarily from contin- search. One interesting problem considered has ental air are marked with a double asterisk. For been the source of precipitation classified accord- all other classifications, precipitation may have ing to air mass. occurred either from maritime or continental air, In 1937 Holzman [2] advanced the hypothesis depending upon the individual circumstances. that the great majority of precipitation comes from maritime air masses. Although meteorologists I. Cold front have generally been willing to accept this hypothe- A. Pre-frontal precipitation sis on the basis of their qualitative familiarity with *1. MT present throughout tropo- atmospheric phenomena, little has been done to sphere determine quantitatively the percentage of pre- **2. cP present throughout tropo- cipitation which can actually be traced to maritime sphere air. Certainly the precipitation from continental 3. MT overriding cP in warm sec- air masses must be measurable and must vary in tor importance from region to region. B. Post-frontal precipitation In the course of an analysis of the role of the 1. MT overriding cP atmosphere in the hydrologic cycle [1], the au- *a. -
Fog and Low Clouds As Troublemakers During Wildfi Res
When Our Heads Are in the Clouds Sometimes water droplets do not freeze in below- Detecting fog from space Up to 60,000 ft (18,000m) freezing temperatures. This happens if they do not have Weather satellites operated by the National Oceanic The fog comes a surface (like a dust particle or an ice crystal) upon and Atmospheric Administration (NOAA) collect data on on little cat feet. which to freeze. This below-freezing liquid water becomes clouds and storms. Cirrus Commercial Jetliner “supercooled.” Then when it touches a surface whose It sits looking (36,000 ft / 11,000m) temperature is below freezing, such as a road or sidewalk, NOAA operates two different types of satellites. over harbor and city Geostationary satellites orbit at about 22,236 miles Breitling Orbiter 3 the water will freeze instantly, making a super-slick icy on silent haunches (34,000 ft / 10,400m) Cirrocumulus coating on whatever it touches. This condition is called (35,786 kilometers) above sea level at the equator. At this and then moves on. Mount Everest (29,035 ft / 8,850m) freezing fog. altitude, the satellite makes one Earth orbit per day, just Carl Sandburg Cirrostratus as Earth rotates once per day. Thus, the satellite seems to 20,000 feet (6,000 m) Cumulonimbus hover over one spot below and keeps its “birds’-eye view” of nearly half the Earth at once. Altocumulus The other type of NOAA satellites are polar satellites. Their orbits pass over, or nearly over, the North and South Clear and cloudy regions over the U.S. -
Air Masses and Fronts
CHAPTER 4 AIR MASSES AND FRONTS Temperature, in the form of heating and cooling, contrasts and produces a homogeneous mass of air. The plays a key roll in our atmosphere’s circulation. energy supplied to Earth’s surface from the Sun is Heating and cooling is also the key in the formation of distributed to the air mass by convection, radiation, and various air masses. These air masses, because of conduction. temperature contrast, ultimately result in the formation Another condition necessary for air mass formation of frontal systems. The air masses and frontal systems, is equilibrium between ground and air. This is however, could not move significantly without the established by a combination of the following interplay of low-pressure systems (cyclones). processes: (1) turbulent-convective transport of heat Some regions of Earth have weak pressure upward into the higher levels of the air; (2) cooling of gradients at times that allow for little air movement. air by radiation loss of heat; and (3) transport of heat by Therefore, the air lying over these regions eventually evaporation and condensation processes. takes on the certain characteristics of temperature and The fastest and most effective process involved in moisture normal to that region. Ultimately, air masses establishing equilibrium is the turbulent-convective with these specific characteristics (warm, cold, moist, transport of heat upwards. The slowest and least or dry) develop. Because of the existence of cyclones effective process is radiation. and other factors aloft, these air masses are eventually subject to some movement that forces them together. During radiation and turbulent-convective When these air masses are forced together, fronts processes, evaporation and condensation contribute in develop between them. -
3 Atmospheric Motion
Final PDF to printer CHAPTER 3 Atmospheric Motion MOTION OF THE EARTH’S ATMOSPHERE has a great influence on human lives by controlling climate, rainfall, weather patterns, and long-range transportation. It is driven largely by differences in insolation, with influences from other factors, including topography, land-sea interfaces, and especially rotation of the planet. These factors control motion at local scales, like between a mountain and valley, at larger scales encompassing major storm systems, and at global scales, determining the prevailing wind directions for the broader planet. All of these circulations are governed by similar physical principles, which explain wind, weather patterns, and climate. Broad-scale patterns of atmospheric circulation are shown here for the Northern Hemisphere. Examine all the components on this figure and think about what you know about each. Do you recognize some of the features and names? Two features on this figure are identified with the term “jet stream.” You may have heard this term watching the nightly weather report or from a captain on a cross-country airline flight. What is a jet stream and what effect does it have on weather and flying? Prominent labels of H and L represent areas with relatively higher and lower air pressure, respectively. What is air pressure and why do some areas have higher or lower pressure than other areas? Distinctive wind patterns, shown by white arrows, are associated with the areas of high and low pressure. The winds are flowing outward and in a clockwise direction from the high, but inward and in a counterclockwise direction from the low. -
Weather Charts Natural History Museum of Utah – Nature Unleashed Stefan Brems
Weather Charts Natural History Museum of Utah – Nature Unleashed Stefan Brems Across the world, many different charts of different formats are used by different governments. These charts can be anything from a simple prognostic chart, used to convey weather forecasts in a simple to read visual manner to the much more complex Wind and Temperature charts used by meteorologists and pilots to determine current and forecast weather conditions at high altitudes. When used properly these charts can be the key to accurately determining the weather conditions in the near future. This Write-Up will provide a brief introduction to several common types of charts. Prognostic Charts To the untrained eye, this chart looks like a strange piece of modern art that an angry mathematician scribbled numbers on. However, this chart is an extremely important resource when evaluating the movement of weather fronts and pressure areas. Fronts Depicted on the chart are weather front combined into four categories; Warm Fronts, Cold Fronts, Stationary Fronts and Occluded Fronts. Warm fronts are depicted by red line with red semi-circles covering one edge. The front movement is indicated by the direction the semi- circles are pointing. The front follows the Semi-Circles. Since the example above has the semi-circles on the top, the front would be indicated as moving up. Cold fronts are depicted as a blue line with blue triangles along one side. Like warm fronts, the direction in which the blue triangles are pointing dictates the direction of the cold front. Stationary fronts are frontal systems which have stalled and are no longer moving. -
Pressure Perturbations and Upslope Flow Over a Heated, Isolated Mountain
4272 MONTHLY WEATHER REVIEW VOLUME 136 Pressure Perturbations and Upslope Flow over a Heated, Isolated Mountain BART GEERTS,QUN MIAO, AND J. CORY DEMKO University of Wyoming, Laramie, Wyoming (Manuscript received 29 January 2008, in final form 14 April 2008) ABSTRACT Surface and upper-air data, collected as part of the Cumulus Photogrammetric, In Situ, and Doppler Observations (CuPIDO) experiment during the 2006 monsoon season around the Santa Catalina Mountains in southeast Arizona, are used to study the diurnal variation of the mountain-scale surface convergence and its thermal forcing. The thermal forcing is examined in terms of a horizontal pressure gradient force, which is derived assuming hydrostatic balance. The mountain is ϳ30 km in diameter, ϳ2 km high, and relatively isolated. The environment is characterized by weak winds, a deep convective boundary layer in the after- noon, and sufficient low-level moisture for orographic cumulus convection on most days. The katabatic, divergent surface flow at night and anabatic, convergent flow during the day are in phase with the diurnal variation of the horizontal pressure gradient force, which points toward the mountain during the day and away from the mountain at night. The daytime pressure deficit over the mountain of 0.5–1.0 mb is hydrostatically consistent with the observed 1–2-K virtual potential temperature excess over the mountain. The interplay between surface convergence and orographic thunderstorms is examined, and the consequence of deep convection (outflow spreading) is more apparent than its possible trigger (en- hanced convergence). 1. Introduction mountain-scale convergence in the CBL and, under suitable stability and cumulus development, but small Significant research has been conducted on flow and enough that the solenoidal flow response to elevated pressure variations around an isolated mountain in heating is quasi-instantaneous. -
Imet-4 Radiosonde 403 Mhz GPS Synoptic
iMet-4 Radiosonde 403 MHz GPS Synoptic Technical Data Sheet Temperature and Humidity Radiosonde Data Transmission The iMet-4 measures air temperature with a The iMet-4 radiosonde can transmit to an small glass bead thermistor. Its small size effective range of over 250 km*. minimizes effects caused by long and short- wave radiation and ensures fast response times. A 6 kHz peak-to-peak FM transmission maximizes efficiency and makes more channels The humidity sensor is a thin-film capacitive available for operational use. Seven frequency polymer that responds directly to relative selections are pre-programmed - with custom humidity. The sensor incorporates a temperature programming available. sensor to minimize errors caused by solar heating. Calibration Pressure and Height The iMet-4’s temperature and humidity sensors are calibrated using NIST traceable references to As recommended by GRUAN3, the iMet-4 is yield the highest data quality. equipped with a pressure sensor to calculate height at lower levels in the atmosphere. Once Benefits the radiosonde reaches the optimal height, pressure is derived using GPS altitude combined • Superior PTU performance with temperature and humidity data. • Lightweight, compact design • No assembly or recalibration required The pressure sensor facilitates the use of the • GRUAN3 qualified (pending) sonde in field campaigns where a calibrated • Status LED indicates transmit frequency barometer is not available to establish an selection and 3-D GPS solution accurate ground observation for GPS-derived • Simple one-button user interface pressure. For synoptic use, the sensor is bias adjusted at ground level. Winds Data from the radiosonde's GPS receiver is used to calculate wind speed and direction. -
Hurricane Response Annex Overview Introduction
TABLE OF CONTENTS SECTION I – HURICANE RESPONSE ANNEX OVERVIEW ............................................................... 2 INTRODUCTION .................................................................................................................................................. 3 PLANNING ASSUMPTIONS ................................................................................................................................... 4 COMMUNITY IMPACTS ........................................................................................................................................ 4 SECTION II – CONCEPT OF OPERATIONS ........................................................................................ 5 DEFINING THE HAZARD ...................................................................................................................................... 5 Tropical Cyclones ..................................................................................................................................................... 5 TIMELINES ........................................................................................................................................................... 6 HURRICANE SEASON ...................................................................................................................................... 6 RESPONDER REENTRY HOUR ......................................................................................................................... 7 SECTION III – ROLES & RESPONSIBILITIES -
Aviation Glossary
AVIATION GLOSSARY 100-hour inspection – A complete inspection of an aircraft operated for hire required after every 100 hours of operation. It is identical to an annual inspection but may be performed by any certified Airframe and Powerplant mechanic. Absolute altitude – The vertical distance of an aircraft above the terrain. AD - See Airworthiness Directive. ADC – See Air Data Computer. ADF - See Automatic Direction Finder. Adverse yaw - A flight condition in which the nose of an aircraft tends to turn away from the intended direction of turn. Aeronautical Information Manual (AIM) – A primary FAA publication whose purpose is to instruct airmen about operating in the National Airspace System of the U.S. A/FD – See Airport/Facility Directory. AHRS – See Attitude Heading Reference System. Ailerons – A primary flight control surface mounted on the trailing edge of an airplane wing, near the tip. AIM – See Aeronautical Information Manual. Air data computer (ADC) – The system that receives and processes pitot pressure, static pressure, and temperature to present precise information in the cockpit such as altitude, indicated airspeed, true airspeed, vertical speed, wind direction and velocity, and air temperature. Airfoil – Any surface designed to obtain a useful reaction, or lift, from air passing over it. Airmen’s Meteorological Information (AIRMET) - Issued to advise pilots of significant weather, but describes conditions with lower intensities than SIGMETs. AIRMET – See Airmen’s Meteorological Information. Airport/Facility Directory (A/FD) – An FAA publication containing information on all airports, seaplane bases and heliports open to the public as well as communications data, navigational facilities and some procedures and special notices. -
NWS Unified Surface Analysis Manual
Unified Surface Analysis Manual Weather Prediction Center Ocean Prediction Center National Hurricane Center Honolulu Forecast Office November 21, 2013 Table of Contents Chapter 1: Surface Analysis – Its History at the Analysis Centers…………….3 Chapter 2: Datasets available for creation of the Unified Analysis………...…..5 Chapter 3: The Unified Surface Analysis and related features.……….……….19 Chapter 4: Creation/Merging of the Unified Surface Analysis………….……..24 Chapter 5: Bibliography………………………………………………….…….30 Appendix A: Unified Graphics Legend showing Ocean Center symbols.….…33 2 Chapter 1: Surface Analysis – Its History at the Analysis Centers 1. INTRODUCTION Since 1942, surface analyses produced by several different offices within the U.S. Weather Bureau (USWB) and the National Oceanic and Atmospheric Administration’s (NOAA’s) National Weather Service (NWS) were generally based on the Norwegian Cyclone Model (Bjerknes 1919) over land, and in recent decades, the Shapiro-Keyser Model over the mid-latitudes of the ocean. The graphic below shows a typical evolution according to both models of cyclone development. Conceptual models of cyclone evolution showing lower-tropospheric (e.g., 850-hPa) geopotential height and fronts (top), and lower-tropospheric potential temperature (bottom). (a) Norwegian cyclone model: (I) incipient frontal cyclone, (II) and (III) narrowing warm sector, (IV) occlusion; (b) Shapiro–Keyser cyclone model: (I) incipient frontal cyclone, (II) frontal fracture, (III) frontal T-bone and bent-back front, (IV) frontal T-bone and warm seclusion. Panel (b) is adapted from Shapiro and Keyser (1990) , their FIG. 10.27 ) to enhance the zonal elongation of the cyclone and fronts and to reflect the continued existence of the frontal T-bone in stage IV. -
GPS-Based Measurement of Height and Pressure with Vaisala Radiosonde RS41
GPS-Based Measurement of Height and Pressure with Vaisala Radiosonde RS41 WHITE PAPER Table of Contents CHAPTER 1 Introduction ................................................................................................................................................. 4 Executive Summary of Measurement Performance ............................................................................. 5 CHAPTER 2 GPS Technology in the Vaisala Radiosonde RS41 ........................................................................................... 6 Radiosonde GPS Receiver .................................................................................................................. 6 Local GPS Receiver .......................................................................................................................... 6 Calculation Algorithms ..................................................................................................................... 6 CHAPTER 3 GPS-Based Measurement Methods ............................................................................................................... 7 Height Measurement ......................................................................................................................... 7 Pressure Measurement ..................................................................................................................... 7 Measurement Accuracy..................................................................................................................... 8 CHAPTER -
3.2 the Forecast Icing Potential (Fip) Algorithm
3.2 THE FORECAST ICING POTENTIAL (FIP) ALGORITHM Frank McDonough *, Ben C. Bernstein, Marcia K. Politovich, and Cory A. Wolff National Center for Atmospheric Research, Boulder, CO 1. Introduction The 70% threshold was chosen to allow for expected model moisture errors and to allow for In-flight icing is a serious hazard to the cold clouds to be found without a model forecast aviation community. It occurs when subfreezing of water saturation. The use of a combination of liquid cloud and/or precipitation droplets freeze to relative humidity with respect to both water and ice the exposed surfaces of an aircraft in flight. Icing may allow for the use of a higher threshold in conditions can occur on large scales or in small future versions of FIP. volumes where conditions may change quickly. Cloud base is found by working upward in the Because of the nature of icing conditions, the need same column until the first level with RH≥80% is for a forecast product with high spatial and found. Since the model boundary layer often has temporal resolution is apparent. RH>80%, even in cloud-free air, FIP begins its The FIP (Forecast Icing Potential) algorithm search for a cloud base at 1000ft (305m) AGL. was developed at the National Center for The threshold of 80% for cloud base identification Atmospheric Research under the Federal Aviation is used to also allow for model moisture errors and Administration’s Aviation Weather Research the expectation that cloud base is found at warmer Program. It uses 20-km resolution Rapid Update temperatures where RH and RHi are more Cycle (RUC) model output to determine the equivalent.