Query: The jet stream controls broad weather patterns, such as high-pressure and low-pressure systems.

Relevant passages:
Extratropical cyclone <=SEP=> Extratropical cyclones , sometimes called mid-latitude cyclones or wave cyclones , are low-pressure areas which , along with the anticyclones of high-pressure areas , drive the weather over much of the Earth . Extratropical cyclones are capable of producing anything from cloudiness and mild showers to heavy gales , thunderstorms , blizzards , and tornadoes . These types of cyclones are defined as large scale ( synoptic ) low pressure weather systems that occur in the middle latitudes of the Earth . In contrast with tropical cyclones , extratropical cyclones produce rapid changes in temperature and dew point along broad lines , called weather fronts , about the center of the cyclone .

Jet stream <=SEP=> Jet streams are fast flowing , narrow , meandering air currents found in the atmosphere of some planets , including Earth . On Earth , the main jet streams are located near the altitude of the tropopause and are westerly winds ( flowing west to east ) . Their paths typically have a meandering shape . Jet streams may start , stop , split into two or more parts , combine into one stream , or flow in various directions including opposite to the direction of the remainder of the jet . The strongest jet streams are the polar jets , at 9 - above sea level , and the higher altitude and somewhat weaker subtropical jets at 10 - . The Northern Hemisphere and the Southern Hemisphere each have a polar jet and a subtropical jet . The northern hemisphere polar jet flows over the middle to northern latitudes of North America , Europe , and Asia and their intervening oceans , while the southern hemisphere polar jet mostly circles Antarctica all year round .   Jet streams are the product of two factors : the atmospheric heating by solar radiation that produces the large scale Polar , Ferrel , and Hadley circulation cells , and the action of the Coriolis force acting on those moving masses . The Coriolis force is caused by the planet 's rotation on its axis . On other planets , internal heat rather than solar heating drives their jet streams . The Polar jet stream forms near the interface of the Polar and Ferrel circulation cells ; while the subtropical jet forms near the boundary of the Ferrel and Hadley circulation cells .   Other jet streams also exist . During the Northern Hemisphere summer , easterly jets can form in tropical regions , typically where dry air encounters more humid air at high altitudes . Low-level jets also are typical of various regions such as the central United States .   Meteorologists use the location of some of the jet streams as an aid in weather forecasting . The main commercial relevance of the jet streams is in air travel , as flight time can be dramatically affected by either flying with the flow or against , which results in significant fuel and time cost savings for airlines . Often , the airlines work to fly ` with ' the jet stream for this reason . Dynamic North Atlantic Tracks are one example of how airlines and air traffic control work together to accommodate the jet steam and winds aloft that results in the maximum benefit for airlines and other users . Clear-air turbulence , a potential hazard to aircraft passenger safety , is often found in a jet stream 's vicinity , but it does not create a substantial alteration on flight times .

Cyclone <=SEP=> In meteorology , a cyclone is a large scale air mass that rotates around a strong center of low atmospheric pressure . Cyclones are characterized by inward spiraling winds that rotate about a zone of low pressure . The largest low-pressure systems are polar vortices and extratropical cyclones of the largest scale ( the synoptic scale ) . Warm-core cyclones such as tropical cyclones and subtropical cyclones also lie within the synoptic scale .  Mesocyclones , tornadoes and dust devils lie within the smaller mesoscale . Upper level cyclones can exist without the presence of a surface low , and can pinch off from the base of the Tropical Upper Tropospheric Trough during the summer months in the Northern Hemisphere . Cyclones have also been seen on extraterrestrial planets , such as Mars and Neptune .  Cyclogenesis describes the process of cyclone formation and intensification . Extratropical cyclones begin as waves in large regions of enhanced mid-latitude temperature contrasts called baroclinic zones . These zones contract and form weather fronts as the cyclonic circulation closes and intensifies . Later in their life cycle , extratropical cyclones occlude 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 jet stream .   Weather fronts mark the boundary between two masses of air of different temperature , humidity , and densities , and are associated with the most prominent meteorological phenomena . Strong cold fronts typically feature narrow bands of thunderstorms and severe weather , and may on occasion be preceded by squall lines or dry lines . Such fronts form west of the circulation center and generally move from west to east ; warm fronts form east of the cyclone center and are usually preceded by stratiform precipitation and fog . Warm fronts move poleward 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 .   Tropical cyclogenesis 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 tornado formation . Waterspouts can also form from mesocyclones , but more often develop from environments of high instability and low vertical wind shear . In the Atlantic and the northeastern Pacific oceans , a tropical cyclone is generally referred to as a hurricane ( from the name of the ancient Central American deity of wind , Huracan ) , in the Indian and south Pacific oceans it is called a cyclone , and in the northwestern Pacific it is called a typhoon .