Uncertainties can be reduced by using models with higher spatial resolution, improving linkages coupling the atmosphere, oceans, and land surface, better reconstruction of paleoclimate, and improved representation of atmospheric chemsitry and vegetation and soils. An air mass is a large region of the atmosphere with a relatively uniform pressure, temperature, and water vapor content. An air mass may cover an area of thousands of kilometers and may be several kilometers thick. In order for this to occur, the source region must be dominated by high pressure. It should also be relatively flat and of uniform composition.
Warm fronts have an average speed of about ten knots, and can move in a series of jumps.
Warm fronts are often preceded by clouds and precipitation. Cold fronts move quickly, with an average speed of 25 knots. If the air behind the occluded front is colder than the air in front of it, then the front is a cold-type occluded front and has characteristics similar to a cold front. If the air behind the front is warmer than the air ahead of it, then the front is a warm-type occluded front and has characteristics similar to a warm front. Clouds tend to form along the edge of an air mass because this is where two separate air masses meet and react with each other.