Fronts mean areas with a noticable increase or decrease in temperture, i.e. warm and cold fronts . Reno is colder in Winter then Sacramento because of the higher elevation. In order to properly compare the temperture of two separate areas, they must have the same elevation. Air Pressure -A barometer measures the weight of the air. A high pressure area is one in which air is present, a low pressure area is one which exhibits no air, such as a vacuum.
Pressure is measured to the tenth.
The limits of measurement, however, are 1050 millimars as the highest possible amount, and 960 millibars as the lowest. Mars has a measurement of about 50.5 millibars, while Venus exhibits twenty times Earth's pressure, enough to crush a human being. Different air contents in each, however, make them both unliveable. This is measured in units of millibars by a device called a barometer. At sea surface elevation, the average atmospheric pressure is around 1000 millibars.