In solar-terrestrial terms, the optimum high frequency radio wave with a 3000 km range, which reflects only once from the ionosphere (single hop transmission)
- Browse Related Terms: aliasing, ARINC, Centimeter Burst, Extreme Ultraviolet (EUV), Extremely low frequency (ELF), High Frequency (HF), Low Frequency, M 3000, Medium Frequency, Polar Cap Absorption (PCA), PTN, Riometer, U Burst, Ultra High Frequency (UHF), Ver High Frequency (VHF), very low frequency (VLF), Visual Spectrum, White Light (WL)
The name given to cirrocumulus clouds with small vertical extent and composed of ice crystals. The rippled effect gives the appearance of fish scales.
- Browse Related Terms: Brocken Specter, CI, Cirrocumulus, Cirrostratus, Cirrus, Glory, High Clouds, Iridescence, Iridescent Clouds, Mackeral Sky, Middle Clouds
(abbrev. MJO)- Tropical rainfall exhibits strong variability on time scales shorter than the seasonal El NiÃ±o-Southern Oscillation (ENSO). These fluctuations in tropical rainfall often go through an entire cycle in 30-60 days, and are referred to as the Madden-Julian Oscillation or intraseasonal oscillations. The intraseasonal oscillations are a naturally occurring component of our coupled ocean-atmosphere system. They significantly affect the atmospheric circulation throughout the global Tropics and subtropics, and also strongly affect the wintertime jet stream and atmospheric circulation features over the North Pacific and western North America. As a result, they have an important impact on storminess and temperatures over the United States. During the summer these oscillations have a modulating effect on hurricane activity in both the Pacific and Atlantic basins.
- Browse Related Terms: General Circulation, Intraseasonal Oscillation, Klystron, LLJ, Low Level Jet, Madden-Julian Oscillation, MJO
(Great Lakes Marine Forecast) - A National Weather Service coded summary appended to each of the Great Lakes Open Lakes forecasts.
- Browse Related Terms: AFD, Area Forecast Discussion, GLF, GLS, Great Lakes Marine Forecast (MAFOR), Great Lakes Storm Summary, Great Lakes Weather Broadcast, LAWEB, MAFOR, Marine Weather Statement, National Weather and Crop Summary, Nearshore Forecast, Open Lakes Forecast, Tropical Weather Summary
In solar-terrestrial terms, a geomagnetic and/or cosmic storm has been associated with this flare
- Browse Related Terms: Active Longitude, Active Region (AR), burst, Comprehensive Flare Index (CFI), H-Alpha, Homologous Flares, Hyder Flare, Limb Flare, Loop Prominence System, LPS, Magflare, Microwave Burst, Post-Flare Loops, White Light Flare, X-Ray Background, X-Ray Burst, X-Ray Flare Class
In solar-terrestrial terms, a relatively smooth excursion of the H (horizontal) component of the geomagnetic field away from and returning to quiet levels.
- Browse Related Terms: ASAPTRAN, BR, Crochet, Direct Solar Radiation, Fugitive dust, Geomagnetic Elements, Geomagnetic Storm, H-component of the Geomagnetic Field, Magnetic Bay, NWD, RDS, RTRN, Sudden Commencement (SC), Sudden Impulse (SI+ or SI-)
In solar-terrestrial terms, the boundary layer between the solar wind and the magnetosphere.
- Browse Related Terms: Active Dark Filament (ADF), Active Prominence, Active Prominence Region (APR), AP Index, Auroral Oval, Central Meridian Passage (CMP), Continuum Storm (CTM), Differential Rotation, Disappearing Solar Filament (DSF), Eruptive Prominence on Limb (EPL), Flare, Gradual Commencement, High-Speed Stream, Limb, Magnetopause, Plagenil, Proton Event, Quiescent Prominence (Filament), Solar Coordinates, Solar Cycle, Solar Sector Boundary (SSB), SPOTNIL, Syzygy
In solar-terrestrial terms, the magnetic cavity surrounding the earth, carved out of the passing solar wind by virtue of the geomagnetic field, which prevents, or at least impedes, the direct entry of the solar wind plasma into the cavity
Also listed in:
The times of 0000, 0600, 1200, and 1800 UTC. Also known as the standard synoptic times.
- Browse Related Terms: Climate Diagnostics Center, Coordinated Universal Time (UTC), GMT, Intermediate Synoptic Times, Main Synoptic Times, MAINT, NAM, Standard Synoptic Times, Universal Time (UT), UTC, Z, Zulu (Z) Time
A general term including extensive inundation and property damage. (Usually characterized by the evacuation of people and livestock and the closure of both primary and secondary roads.)
Also listed in:
A hurricane which reaches Category 3 (sustained winds greater than 110 mph) on the Saffir/Simpson Hurricane Scale.
A hurricane that is classified as Category 3 or higher.
- Browse Related Terms: Center / Vortex Fix, Central North Pacific Basin, Direct Hit, Eastern North Pacific Basin, Eye, Eyewall / Wall Cloud, Hurricane Season, Indirect Hit, Invest, Landfall, Major Hurricane, Radius of Maximum Winds, Strike, Synoptic Track, Tropical Cyclone Plan of the Day
Moist Adiabatic Lapse Rate- The rate at which the temperature of a parcel of saturated air decreases as the parcel is lifted in the atmosphere. The moist adiabatic lapse rate (abbreviated MALR) is not a constant like the dry adiabatic lapse rate but is dependent on parcel temperature and pressure.
- Browse Related Terms: Absolutely Stable Air, Absolutely Unstable Air, Adiabatic Lapse Rate, AFRED, CCL, Conditionally Unstable Air, Convective Condensation Level, DALR, Dry Adiabatic Lapse Rate, LCL, Lifting Condensation Level, MALR, Moist Adiabat, Moist Adiabatic Lapse Rate, Neutral Stability
Rounded, smooth, sack-like protrusions hanging from the underside of a cloud (usually a thunderstorm anvil). Mammatus clouds often accompany severe thunderstorms, but do not produce severe weather; they may accompany non-severe storms as well.
- Browse Related Terms: Anvil, Anvil Crawler, Anvil Zits, Back-sheared Anvil, Blue Watch or Blue Box, Cumuliform Anvil, Knuckles, Mammatus Clouds, Mushroom, Orphan Anvil, Positive Cloud to Ground Lightning, Spin-Up, SPRD, Vort Max, Wildfire