Editing Surface weather analysis (section)

==== Low pressure ====
Low-pressure systems, also known as [[cyclone]]s, are located in minima in the pressure field.  Rotation is inward at the surface and counterclockwise in the [[northern hemisphere]] as opposed to inward and clockwise in the [[southern hemisphere]] due to the [[Coriolis force]]. Weather is normally unsettled in the vicinity of a cyclone, with increased cloudiness, increased winds, increased temperatures, and upward motion in the atmosphere, which leads to an increased chance of precipitation. [[Polar low]]s can form over relatively mild ocean waters when cold air sweeps in from the ice cap. The relatively warmer water leads to upward convection, causing a low to form, and precipitation usually in the form of snow. Tropical cyclones and winter storms are intense varieties of low pressure. Over land, [[thermal low]]s are indicative of hot weather during the summer.<ref>BBC Weather. [http://www.bbc.co.uk/weather/features/basics_lowpressure.shtml Weather Basics - Low Pressure.] Retrieved on 2007-05-05.</ref>