Geography of Ohio 
195 
too much or too little rain. But a record of crops for a series of 
years shows that no particular part of Ohio has any advantage 
over other parts, in this respect. 
WINDS 
Someone once said, and the assertion has been current through 
the centuries, ^^The wind bloweth where it listeth.’^ The physics 
of the atmosphere was not well understood in Biblical times. 
The atmosphere moves according to law. In Ohio we are in the 
track of a very regular wind belt, the prevailing westerlies. 
If the wind always blew from the west, it would grow very mo- 
notonous, but the prevailing direction may be from the west and 
yet a good many variations be introduced. These variations 
from the prevailing wind give the most interesting phases 'of 
this subject. 
Cause of air currents. As to their origin, winds are classified 
under two heads, highs’^ and ^ Tows’’, the names having no con- 
nection with their velocity. The atmosphere moves not because 
there is any external force which gives it impulsion, but because 
of its tendency to maintain equilibrium. The fluctuation of 
wind direction represents the effort of the atmosphere to return 
to a state of equilibrium. There has been an unbalancing some- 
where in its body, and the atmosphere is on the move, trying to 
establish a condition of rest ; the unbalancing is due to a difference 
in the relative weight of adjacent parts of the atmosphere. 
The reason why the atmosphere does not, at all places, have a 
uniform weight is closely connected with the question of heat- 
radiation from the earth’s surface; there may be other causes, but 
this is known to be one. Take the roof off an ice-house, sweep 
the sawdust away, and you will cool the nearby atmosphere. 
That atmosphere, growing cool, becomes heavier; adjacent to it 
is lighter atmosphere, which the heavier atmosphere displaces. 
That is the principle of the winds. Somewhere the atmosphere 
has become heavier and it pushes out; or somewhere the atmos- 
phere has grown warmer and consequently lighter, and it is 
displaced by the heavier. The movement arising from either 
cooling or warming is an effort to establish equilibrium. The 
weather in Ohio, in its variations from day to day, is largely con- 
nected with this question of atmospheric density, or high and 
low pressure areas. 
