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两个性质不同的气团相遇时,它们中间就有一个过渡区域,这一过渡区域被称为“锋”。锋近地面的宽度只有几十千米,到高层虽可达到200千米～400千米,但相对两侧数千米的冷暖气团来说,这个过渡区域相当狭小,恰似一薄面,故而人们又称锋为锋面。锋面一侧的暖气团因温度高、气压低、密度小,位于锋面的上部,冷气团则温度低、气压高、密度大,位于下部。由于锋面有坡度,冷暖空气交绥,暖空气可沿坡上升或被迫抬升,且暖空气中含有较多的水汽,空气绝热上升,水汽凝结,易形成云雨天气。又因锋面是各种气象要素水平差异较大地区,能量集中,所以,锋是天气变化剧烈的地带。目前,关于锋有两种分类方法:第一种是根据锋面两侧冷暖气团的移动方向及结构状况,可以分为下列4类:冷锋、暖锋、准静止锋、锢囚锋;第二种是按照它所处的地理位置分类,从北到南分为(北半球):北极(冰洋)锋、温带锋(极锋)、热带
When two air masses of different nature meet each other, there is a transition zone between them, and this transitional zone is called “Feng”. The width of the front near the ground is only a few tens of kilometers, although the high-level can reach 200 km to 400 km, but the opposite sides of several kilometers of cold and warm air masses, the transitional area is quite small, just like a thin surface, so people Called front for the front. Front side of the warm air mass due to high temperature, low pressure, low density, located in the front of the front, cold air mass is low temperature, high pressure, density, located in the lower part. As the front has a gradient, cold and warm air cross-talk, warm air may rise along the slope or forced up, and the warm air contains more water vapor, air heat up, water vapor condensation, easy to form cloud rainy weather. Because of the frontier is a large area of different meteorological elements of different levels, the energy concentration, so the front is dramatic changes in the weather. At present, there are two classification methods for Feng: The first one is based on the moving direction and structure of the heating and cooling air masses on both sides of the front, and can be divided into the following four categories: cold front, warm front, quasi-static front and occlusion front; Is classified according to its geographical location, from north to south is divided into (Northern Hemisphere): Arctic (Arctic) front, temperate front (extreme front), tropical