forming {TAIL ~ a first difference} which is a function of the actual temperature and {HEAD ~ the first model temperature} 
forming { TAIL ~ a first difference } which is a function of the actual temperature and { HEAD ~ the first model temperature }
OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD