Hail is a form of solid precipitation. It is distinct from ice pellets, though the two are often confused. It consists of balls or irregular lumps of ice, each of which is called a hailstone. Ice pellets generally fall in cold weather, while hail growth is greatly inhibited during low surface temperatures.
A radiosonde is a battery-powered telemetry instrument carried into the atmosphere usually by a weather balloon that measures various atmospheric parameters and transmits them by radio to a ground receiver. Modern radiosondes measure or calculate the following variables: altitude, pressure, temperature, relative humidity, wind, cosmic ray readings at high altitude and geographical position (latitude/longitude). Radiosondes measuring ozone concentration are known as ozonesondes.
NEXRAD or Nexrad is a network of 159 high-resolution S-band Doppler weather radars operated by the National Weather Service (NWS), an agency of the National Oceanic and Atmospheric Administration (NOAA) within the United States Department of Commerce, the Federal Aviation Administration (FAA) within the Department of Transportation, and the U.S. Air Force within the Department of Defense. Its technical name is WSR-88D.
Weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, and estimate its type. Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the intensity of the precipitation. Both types of data can be analyzed to determine the structure of storms and their potential to cause severe weather.
The Meteor spacecraft are weather observation satellites launched by the Soviet Union and Russia. The Meteor satellite series was initially developed during the 1960s. The Meteor satellites were designed to monitor atmospheric and sea-surface temperatures, humidity, radiation, sea ice conditions, snow-cover, and clouds. Between 1964 and 1969, a total of eleven Soviet Union Meteor satellites were launched.
The National Severe Storms Laboratory (NSSL) is a National Oceanic and Atmospheric Administration (NOAA) weather research laboratory under the Office of Oceanic and Atmospheric Research. It is one of seven NOAA Research Laboratories (RLs).
In meteorology, a heat burst is a rare atmospheric phenomenon characterized by a sudden, localized increase in air temperature near the Earth's surface. Heat bursts typically occur during night-time and are associated with decaying thunderstorms. They are also characterized by extremely dry air and are sometimes associated with very strong, even damaging, winds.
Willis Island is the only permanently inhabited island in the Coral Sea Islands Territory, an external territory of Australia, located beyond the Great Barrier Reef in the Coral Sea. The island is located some 450 kilometres (280 mi) east of Cairns, Queensland. It is the southernmost of the Willis Islets, a group of three islands which with their associated sandy cays stretch in a NNE to SSW line for about 12 kilometres (7.5 mi). Willis Island itself is aligned NW to SE and is about 500 metres (1,600 ft) long by 150 metres (490 ft) wide, 7.7 hectares in area, rising to about 9 metres (30 ft) above sea level.
The Canadian weather radar network consists of 33 weather radars spanning Canada's most populated regions. Their primary purpose is the early detection of precipitation, its motion and the threat it poses to life and property.
A lightning detector is a device that detects lightning produced by thunderstorms. There are three primary types of detectors: ground-based systems using multiple antennas, mobile systems using a direction and a sense antenna in the same location, and space-based systems. The first such device was invented in 1894 by Alexander Stepanovich Popov. It was also the first radio receiver in the world.
ARMOR Doppler weather radar is a C-Band, Dual-Polarimetric Doppler Weather Radar, located at the Huntsville International Airport in Huntsville, Alabama. The radar is a collaborative effort between WHNT-TV and the University of Alabama in Huntsville. Live data for the radar is only available to a limited audience, such as UAH employees and NWS meteorologists. All ARMOR data is archived at the National Space Science and Technology Center located on the UAH campus.
Convective storm detection is the meteorological observation, and short-term prediction, of deep moist convection (DMC). DMC describes atmospheric conditions producing single or clusters of large vertical extension clouds ranging from cumulus congestus to cumulonimbus, the latter producing thunderstorms associated with lightning and thunder. Those two types of clouds can produce severe weather at the surface and aloft.
OU-PRIME was an advanced Doppler weather radar. It was completed in January 2009 after a ten-month construction period and commissioned on April 4, 2009. It was operated by the Advanced Radar Research Center (ARRC) at the University of Oklahoma (OU). The radar was manufactured by Enterprise Electronics Corporation to provide OU students and faculty a platform for research and education in the field of radar meteorology. This C-band polarimetric radar has some of the highest resolution data of any C-band weather radar in the United States.
The 2020–21 Australian region cyclone season was a below average but very deadly season when most tropical cyclones formed in the Southern Indian Ocean and Pacific Oceans between 90°E and 160°E. It produced 8 tropical cyclones with 3 strengthening into severe tropical cyclones. However, it featured the region's third-deadliest cyclone on record—Cyclone Seroja, which brought severe floods and landslides to southern Indonesia and East Timor. The season officially began on 1 November 2020 and started with the formation of Tropical Low 01U on 24 November within the basin, which would later become Tropical Storm Bongoyo in the South-West Indian Ocean, and ended with the dissipation of a tropical low on 24 April, 6 days before the season ended on 30 April. However, a tropical cyclone could form at any time between 1 July 2020 and 30 June 2021 and would count towards the season total. During the season, tropical cyclones were officially monitored by one of the three tropical cyclone warning centres (TCWCs) for the region which are operated by the Australian Bureau of Meteorology, National Weather Service of Papua New Guinea and the Indonesian Agency for Meteorology, Climatology and Geophysics. The United States Joint Typhoon Warning Center (JTWC) and other national meteorological services including Météo-France also monitored the basin during the season.
A tornadic debris signature (TDS), often colloquially referred to as a debris ball, is an area of high reflectivity on weather radar caused by debris lofting into the air, usually associated with a tornado. A TDS may also be indicated by dual-polarization radar products, designated as a polarimetric tornado debris signature (PTDS). Polarimetric radar can discern meteorological and nonmeteorological hydrometeors and the co-location of a PTDS with the enhanced reflectivity of a debris ball are used by meteorologists as confirmation that a tornado is occurring.
Multifunction Phased Array Radar (MPAR) was an experimental Doppler radar system that utilized phased array technology. MPAR could scan at angles as high as 60 degrees in elevation, and simultaneously track meteorological phenomena, biological flyers, non-cooperative aircraft, and air traffic. From 2003 through 2016, there was one operational MPAR within the mainland United States—a repurposed AN/SPY-1A radar set loaned to NOAA by the U.S. Navy. The MPAR was decommissioned and removed in 2016.
Project NIMROD was a meteorological field study of severe thunderstorms and their damaging winds conducted by the National Center for Atmospheric Research (NCAR). It took place in the Greater Chicago area from May 15 to June 30, 1978. Data collected was from single cell thunderstorms as well as mesoscale convective systems, such as bow echoes. Using Doppler weather radars and damage clues on the ground, the team studied mesocyclones, downbursts and gust fronts. NIMROD was the first time that microbursts, very localized strong downdrafts under thunderstorms, were detected; this helped improve airport and public safety by the development of systems like the Terminal Doppler Weather Radar and the Low-level windshear alert system.
The 2021–22 Australian region cyclone season, despite a high number of tropical lows forming, was slightly below-average in terms of activity, with ten tropical cyclones forming, two of which intensified further into severe tropical cyclones. The season began from 1 November 2021 and ended on 30 April 2022, but a tropical cyclone could form at any time between 1 July 2021 and 30 June 2022 and would count towards the season total. During the season, tropical cyclones will be officially monitored by one of the three tropical cyclone warning centres (TCWCs) for the region which are operated by the Australian Bureau of Meteorology, National Weather Service of Papua New Guinea and the Indonesian Agency for Meteorology, Climatology and Geophysics. The United States Joint Typhoon Warning Center (JTWC) and other national meteorological services including Météo-France and the Fiji Meteorological Service also monitored the basin during the season.
The 2022–23 Australian region cyclone season was the fourth consecutive season to have below-average activity in terms of named storms. The season officially started on 1 November 2022 and finished on 30 April 2023, however, a tropical cyclone could form at any time between 1 July 2022 and 30 June 2023 and would count towards the season total, as Tropical Cyclone 01U proved in July 26. During the season, tropical cyclones were officially monitored by one of the three tropical cyclone warning centres (TCWCs) for the region which are operated by the Australian Bureau of Meteorology, National Weather Service of Papua New Guinea and the Indonesian Agency for Meteorology, Climatology and Geophysics. The United States Joint Typhoon Warning Center (JTWC) and other national meteorological services including Météo-France and the Fiji Meteorological Service also monitored the basin during the season.
Dušan S. Zrnić is an American engineer of Yugoslav origin, head of the Doppler Weather Radar and Remote Sensing Research Group at the National Severe Storms Laboratory (NSSL) as well as assistant professor of electrical engineering and meteorology at the University of Oklahoma in Norman, Oklahoma. His research interests include circuit design, applied mathematics, magnetohydrodynamics, radar signal processing, and systems design.
