The water source comes from the low latitudesouth of the subtropical high over the west Pacific and the Indian Ocean.
水汽的源地可以追朔到相当远 ，主要来自西太平洋副热带高压南部低纬热带地区和印度洋洋面。
2
Aerosols disperse well in the atmosphere along the latitude lines as the winds blow west to east.But moving them north and south takes more time.
气溶胶在大气中随着纬度线由西向东易于扩散，但是将它们南北向传播则需要很多时间。
3
The sun must be very high in the sky and it can not be seen at a latitude above 55degrees north (which includes Scotland and much of Canada) or below 55 degrees south.