They are drawn as solid red lines. They are sketched according to reported temperatures. Isotherms are labeled in the same manner as contours at the end of each line and in a small break near the top of closed loops. In regions of sparse data an estimate of the isotherm pattern becomes necessary. As we discussed earlier, temperatures at selected points are fre-quently used in extrapolating the heights of various upper levels.
Wind determines the pattern isotherms take and their speed of movement.
Their speed is somewhat less than the wind speed. The addition or subtraction of heat. Adiabatic changes due to lifting or sub-sidence. As warm air is advected toward a cold region, it tends to be cooled, and cold air advected toward warm regions tends to be warmed. At the same time, instability results.