Cyclone

In <a href="/facts/Meteorology/xblFr28q">meteorology</a>, a cyclone is a large <a href="/facts/Air_mass/8Yrr84Ip">air mass</a> that rotates around a strong center of low <a href="/facts/Atmospheric_pressure/wJLMSaVG">atmospheric pressure</a>, counterclockwise in the <a href="/facts/Northern_Hemisphere/EFwyqL25">Northern Hemisphere</a> and clockwise in the <a href="/facts/Southern_Hemisphere/QfJ4z9L5">Southern Hemisphere</a> as viewed from above (opposite to an <a href="/facts/Anticyclone/wBufWaAW">anticyclone</a>). Cyclones are characterized by inward-spiraling winds that rotate about a zone of <a href="/facts/Low_pressure/rphmr6qP">low pressure</a>. The largest low-pressure systems are <a href="/facts/Polar_vortices/RM34TWNk">polar vortices</a> and <a href="/facts/Extratropical_cyclone/4c5Y4hoJ">extratropical cyclones</a> of the largest scale (the <a href="/facts/Synoptic_scale/PMYwbEWA">synoptic scale</a>). Warm-core cyclones such as <a href="/facts/Tropical_cyclone/FQzVXly7">tropical cyclones</a> and <a href="/facts/Subtropical_cyclone/mUbEzUlu">subtropical cyclones</a> also lie within the synoptic scale. <a href="/facts/Mesocyclone/D9BckQcS">Mesocyclones</a>, <a href="/facts/Tornado/HSGNQzHa">tornadoes</a>, and <a href="/facts/Dust_devil/NEQ1TdAU">dust devils</a> lie within the smaller <a href="/facts/Mesoscale_meteorology/E0Tdj8SK">mesoscale</a>.
Upper level cyclones can exist without the presence of a surface low, and can pinch off from the base of the <a href="/facts/Tropical_upper_tropospheric_trough/DoUfgs0w">tropical upper tropospheric trough</a> during the summer months in the <a href="/facts/Northern_Hemisphere/EFwyqL25">Northern Hemisphere</a>. Cyclones have also been seen on extraterrestrial planets, such as <a href="/facts/Mars/AQGtVvz0">Mars</a>, <a href="/facts/Jupiter/95m7XjMT">Jupiter</a>, and <a href="/facts/Neptune/1eucwHIC">Neptune</a>. <a href="/facts/Cyclogenesis/qYHkCaKX">Cyclogenesis</a> is the process of cyclone formation and intensification. <a href="/facts/Extratropical_cyclones/4c5Y4hoJ">Extratropical cyclones</a> begin as waves in large regions of enhanced mid-latitude temperature contrasts called <a href="/facts/Baroclinity/kW8Anrsg">baroclinic zones</a>. These zones contract and form <a href="/facts/Weather_front/n4PXdp1f">weather fronts</a> as the cyclonic circulation closes and intensifies. Later in their life cycle, extratropical cyclones <a href="/facts/Occluded_front/mFv6XDtH">occlude</a> as cold air masses undercut the warmer air and become cold core systems. A cyclone's track is guided over the course of its 2 to 6 day life cycle by the steering flow of the subtropical <a href="/facts/Jet_stream/cVqkU0V3">jet stream</a>.
Weather fronts mark the boundary between two masses of air of different <a href="/facts/Temperature/QyGe4gmj">temperature</a>, <a href="/facts/Humidity/Nwb28VlT">humidity</a>, and <a href="/facts/Densities/92p6hh9I">densities</a>, and are associated with the most prominent <a href="/facts/Meteorological_phenomena/LQzkjgWv">meteorological phenomena</a>. Strong cold fronts typically feature narrow bands of <a href="/facts/Thunderstorm/F6hUzuAu">thunderstorms</a> and <a href="/facts/Severe_weather/9kD3FWWU">severe weather</a>, and may on occasion be preceded by <a href="/facts/Squall_line/vn1lU2uY">squall lines</a> or <a href="/facts/Dry_line/Iwu6fJE2">dry lines</a>. Such fronts form west of the circulation center and generally move from west to east; <a href="/facts/Warm_front/Q0Gq9wkI">warm fronts</a> form east of the cyclone center and are usually preceded by <a href="/facts/Stratus_cloud/xGz9XQNU">stratiform</a> <a href="/facts/Precipitation/uq3nGQc8">precipitation</a> and <a href="/facts/Fog/mrIdyIc7">fog</a>. Warm fronts move <a href="/facts/Geographical_pole/dTShPqll">poleward</a> ahead of the cyclone path. Occluded fronts form late in the cyclone life cycle near the center of the cyclone and often wrap around the storm center.
<a href="/facts/Tropical_cyclogenesis/4fTuGsuE">Tropical cyclogenesis</a> describes the process of development of tropical cyclones. Tropical cyclones form due to latent heat driven by significant thunderstorm activity, and are warm core. Cyclones can transition between extratropical, subtropical, and tropical phases. Mesocyclones form as warm core cyclones over land, and can lead to <a href="/facts/Tornado/HSGNQzHa">tornado</a> formation. <a href="/facts/Waterspout/AyLyQ0Wd">Waterspouts</a> can also form from mesocyclones, but more often develop from environments of high instability and low vertical <a href="/facts/Wind_shear/3d3Qkma9">wind shear</a>. In the Atlantic and the northeastern Pacific oceans, a tropical cyclone is generally referred to as a <a href="/facts/Hurricane/FQzVXly7">hurricane</a> (from the name of the ancient Central American deity of wind, <a href="/facts/Huracan/s7Vs5GtX">Huracan</a>), in the Indian and south Pacific oceans it is called a cyclone, and in the northwestern Pacific it is called a <a href="/facts/Typhoon/xGfFa6H7">typhoon</a>.
The growth of instability in the vortices is not universal. For example, the size, intensity, moist-convection, surface evaporation, the value of potential temperature at each potential height can affect the nonlinear evolution of a vortex.

Cyclone open-in-new

Cyclone