Isobars and isotherms are lines on weather maps which represent patterns of pressure and temperature, respectively. They show how temperature and pressure are changing over space and so help describe the large-scale weather patterns across a region in the map.
Convergence and divergence roughly determine where air will be sinking or rising. Rising air is associated with clouds and precipitation; sinking air is associated with clear, calm conditions and good weather.
1.6c Air Masses
An air mass is a large uniform volume of air that has consistent properties of density, temperature, and humidity, compared to the air surrounding this air mass which may have different properties.
A front describes the boundary between two air masses containing different temperature and/or water vapor content.
1.6e Jet Streams
Jets are fast moving ribbons of air high up in the atmosphere. They are responsible for transporting highs and lows. They affect precipitation and temperatures, and they mark boundaries between massive air masses.