That means they've been spraying, off beyond your area, and the wind brings it in. This is a popular method now, because too many people were noticing them spraying directly overhead.
Hii ndiyo jia inayotumiwa sahi kwasababu walikuwa wanaonekana wakifukiza juu ya kila mtu.. Wakifanya hivi inaathiri hali ya hewa na kulingana na fukizo wanazotumia italeta joto nyingi ama baridi zaidi.