Physical world and mathematics

Hurricane Research Division

The Hurricane Research Division, founded as the National Hurricane Research Project in 1955, is a NOAA unit in Florida that flies Hurricane Hunter aircraft to improve hurricane forecasting.

Hurricane Rita

Hurricane Rita was a powerful Category 5 Atlantic hurricane of 2005 that devastated southwestern Louisiana and southeastern Texas with an estimated $9.4 billion in damage.

Hurricane Sally

Hurricane Sally was a Category 2 hurricane that struck Gulf Shores, Alabama, on September 16, 2020, moving so slowly it dropped up to 30 inches of rain, causing $7.3 billion in damage.

Hurricane Sandy

Hurricane Sandy, also known as Superstorm Sandy, was the largest Atlantic hurricane on record, striking New Jersey in October 2012 and causing more than $50 billion in losses.

Hurricane shutter

A hurricane shutter, also called a storm shutter, is a protective covering over windows and doors that blocks windborne debris during hurricanes and similar windstorms.

Hurricane Stan

Hurricane Stan was a small Category 1 hurricane of the record 2005 Atlantic season that struck southern Mexico, killing over 1,000 people through floods and landslides across Central America.

Hurricane Tomas

Hurricane Tomas was a Category 2 Atlantic hurricane of October and November 2010 that struck the Windward Islands and passed near Haiti, causing 43 deaths.

Hurricane Weather Research and Forecasting model

The Hurricane Weather Research and Forecasting model (HWRF) was NOAA's storm-following regional model providing track and intensity guidance for tropical cyclones from 2007 to 2023, when HAFS replaced it.

Hurricane Wilma

Hurricane Wilma was the most intense Atlantic hurricane on record, with 882 mb pressure and 185 mph winds, striking Mexico's Yucatan and Florida in October 2005.

Hurst exponent

The Hurst exponent, or Hurst parameter and Hurst coefficient, is a number between 0 and 1 measuring long-range memory in a time series, named for hydrologist Harold Edwin Hurst.

Hurwitz's theorem (composition algebras)

Hurwitz's theorem is Adolf Hurwitz's 1898 classification of real composition algebras: their dimensions are only 1, 2, 4, or 8, namely the reals, complexes, quaternions, and octonions.

Sep 20, 2026

Huw M. L. Davies

Huw M. L. Davies is a Welsh-born organic chemist and Asa Griggs Candler Professor at Emory University who developed donor/acceptor rhodium carbene chemistry for catalytic, site-selective C–H functionalization.

Huygens–Fresnel principle

The Huygens–Fresnel principle, also called Huygens' principle, states that every point on a wave front acts as a source of secondary wavelets, whose sum predicts diffraction.

Huygens' metasurface

A Huygens' metasurface is an electrically thin engineered sheet of subwavelength polarizable particles carrying electric and magnetic surface currents, enabling reflectionless wave transformation, introduced by Pfeiffer and Grbic in 2013.

HV 2112

HV 2112 is a Mira-like variable star in the Small Magellanic Cloud with a period of about 600 days, proposed in 2014 as a Thorne–Żytkow object candidate.

HY-2 (satellite)

HY-2, also known as Haiyang-2 (海洋二号), is a Chinese series of ocean dynamic environment satellites carrying radar altimeters, scatterometers, and radiometers to measure sea surface height, winds, and temperature; the first, HY-2A, launched in 2011.

Hyades (star cluster)

The Hyades (Melotte 25, Caldwell 41) is the nearest open star cluster to Earth, about 150 light-years away in Taurus, where its stars form the V-shaped face of the Bull.

Hyaloclastite

Hyaloclastite is a volcanic rock made of sharp-edged glass fragments that form when lava cools so fast on contact with water or ice that it shatters.

Hybrid automaton

A hybrid automaton is a mathematical model combining continuous dynamics described by differential equations with discrete events, extending finite-state machines; it was introduced at Cornell in 1993.

Hybrid functional

A hybrid functional is an exchange-correlation functional in Kohn-Sham density functional theory that mixes exact Hartree-Fock exchange with semilocal terms, introduced by Axel Becke in 1993 and widely used in chemistry.

Hybrid improper ferroelectricity

Hybrid improper ferroelectricity is a mechanism in which spontaneous electric polarization arises through trilinear coupling of a polar mode to two nonpolar octahedral distortions in layered perovskite oxides.

Hybrid inflation

Hybrid inflation is a class of cosmological inflation models introduced by Andrei Linde in 1994, in which a second, waterfall field ends inflation abruptly at a critical point.

Hybrid logic

Hybrid logic is a family of extensions of modal logic in which formulas can name the possible worlds, times, or states at which they are evaluated.

Hybrid organic–inorganic perovskite

A hybrid organic–inorganic perovskite (HOIP) is a crystalline perovskite material with organic components, first structurally characterized in 1978 and best known as the basis of perovskite solar cells.

Sep 29, 2026

Hybridizable discontinuous Galerkin method

The hybridizable discontinuous Galerkin (HDG) method is a discontinuous Galerkin finite element method for partial differential equations, reported by Cockburn, Gopalakrishnan, and Lazarov in 2009.

Hycean planet

A Hycean planet, or Hycean world, is a proposed class of habitable sub-Neptune exoplanet with a water ocean under a hydrogen-rich atmosphere, theorized in 2021.

HYCOM

HYCOM (HYbrid Coordinate Ocean Model) is an ocean general circulation model that switches its vertical coordinate with location, used for global ocean nowcasting and operational hurricane prediction.

Hydantoin

Hydantoin (imidazolidine-2,4-dione) is a five-membered heterocyclic compound with formula C₃H₄N₂O₂, isolated by Baeyer in 1861 and valued as a drug scaffold, including the anticonvulsant phenytoin.

Hydra (constellation)

Hydra is the largest of the 88 constellations, a long, faint female water snake stretching across more than 3% of the sky, representing the monster slain by Hercules.