碳质气溶胶是由物质的混合物与不同的化学、物理和光学性质。某些有机物质大多是透明的阳光,因此不会导致地球变暖和变冷。其他物质大多是反光的,因此他们的存在在大气中导致地球冷却。然而有物质吸收阳光大气变暖。光吸收碳质气溶胶没有形成一个统一的集团。它们包括烟尘粒子,烟雾,有机化合物,如左旋葡聚糖和腐殖质的幽灵物质都具有不同的光学性质。下图显示了两个化合物的吸收光谱示意图的代表不同群体的光吸收材料。[!(黑色和黄色物质的光吸收谱)[1]][1]一个化合物B1标记有多个均匀分布的吸收系数的可见光谱吸收系数在红色边缘是大约一半的蓝色镶边。另一个复合标签B2更陡峭的斜坡在蓝色的边缘。 It would have a yellowish or light brown color. Think of the yellowish fumes that can be seen when a piece of wood is ignited. Assuming uniform absorption spectrum can lead to significant overestimation of light absorption by atmospheric carbon. So we could instead think of Light absorbing carbonaceous aerosols as two separate groups namely **Black Carbon** with uniform light absorption spectrum and **Brown Carbon** with steep increase in light absorption towards the blue edge. In our example B1 would be assigned to Black Carbon group and B2 would be assigned to the Brown Carbon group. [1]: https://i.stack.imgur.com/co1iK.png