Thermal noise occurs in all transmission media and communication equipment, including passive devices. It arises from random electron motion and is characterized by a uniform distribution of energy over the frequency spectrum with a Gaussian distribution of levels.
An occluded front is formed when a cold front overtakes a warm front. and usually form around mature low-pressure areas. The cold and warm fronts curve naturally poleward into the point of occlusion, which is also known as the triple point.
A warm front is the leading edge of a warmer air mass coming in to replace a cooler one. The general direction in which warm fronts move in North America is from the southwest to the northeast. Since the air temperature increases as a warm front moves in, the air mass is able to hold more moisture and thus brings warmer and more humid characteristics with it.