Changing weather fronts produce severe changes of daily rhythms. Electrical impulses arrive 1-2 days before the weather and create either atmospherics or "positive ions". They are responsible for the epidemic appearance of migraine and of thrombo-embolism. The impact of atmospheric electricity has been assessed in 1000 patients by daily urinalysis of serotonin, 5-HIAA, adrenaline, noradrenaline, histamine, thyroxine, 17-KS, 17-OH, Na, K, creatinine and diureses. The changes found in these 12 parameters allowed a classification of heat reactions into three clinical entities: 1. serotonin hyperproduction causing a typical irritation syndrome: 2. adrenal deficiency producing a typical exhaustion syndrome; 3. hyperthyroidism "Forme fruste" with subclinical "apathetic" thyroid symptoms. These sufferings, typical for Föhn, Tramontana, Sirocco, Sharkiye, Chamssin, Sharav and Santa Ana Winds, are mainly due to positive ionisation of the air. They can be prevented by negative ionising apparatuses or specific drug treatment.