High-pressure area radiation and temperatures rise. At night, the absence of clouds means that outgoing longwave radiation (i.e. heat energy from the surface) is not absorbed, giving cooler diurnal low temperatures in all seasons. When surface winds become light, the subsidence produced directly under a high-pressure system can lead to a buildup of particulates in urban areas under the ridge, leading to widespread haze. If the low level relative humidity rises towards 100 percent overnight, fog can form. Strong, vertically shallow high-pressure systems moving from higher latitudes to lower latitudes in the northern hemisphere are associated with continental arctic air masses. Once
Low pressure molding to keep the desired form upon cooling down. These polyamide materials differ from other thermoplastics in two main areas: One: Viscosity: At processing temperature (410F/210C) the viscosity is very low, typically around 3,000 centipoise (similar to pancake syrup). Low viscosity materials require low injection pressure in order to inject into a cavity. In fact it is normal to use a simple gear pump to inject the polyamide material. Low injection pressure is paramount, when over-molding relatively fragile electronic component. Two: Adhesion: Polyamide materials are basically high performance hot-melt adhesives. The adhesive properties of polyamide is what seals a chosen substrate.