If the Isotherms run nearly parallel, that is, east and west, there will
most likely be no change in the temperature. Southerly to east winds
prevail west of the nearly north and south line, passing through the
middle of a “high” and also east of a like line passing through the
middle of a “low.”
To the west of a nearly north and south line passing through the middle
of a “low,” northerly to westerly winds prevail. We will find the same
condition prevailing to the east of a line passing through the center of
a “high.”
[Illustration:
Fig. 55
]
When we find an absence of decidedly energetic “lows” and “highs,” this
is an indication of the continuance of existing weather. We can expect
this state of the atmosphere until later maps show a beginning of a
change, usually first appearing in the west.