Opposite is a map of the
annual pan rates of evaporation in (inches) across the United
States, which as can be seen from the map of the world's deserts
lies within approximately the same latitudes as the major deserts
of the world.
In a desert region like Tuscon, Arizona, which lies within the
Sonoran Desert, the average annual evaporation is roughly 100
inches or 2.5 m, which is the amount of annually evaporation that
is used in this invention for comparative purposes for all
Evaporation is the changing of water from a liquid state to a gas.
It is usually used to indicate a state change below the boiling
point of water. The evaporation rate can be measured by noting the
change in the depth of water in a glass, a pail, a puddle or a
swimming pool over a given time period (usually a day). Placing a
ruler in any of these gives a scale one can use to read the drop
in the surface elevation in a day or more.
The 8 largest hot deserts encompass an area of 15,559,000 km2. If
2.5 m of water evaporated from each of these deserts this would
make 15,559,000 km2 X .0025 km or 38897.5 km3 of water that would
Latent heat is the amount of energy in the form of heat released
or absorbed by a chemical substance during a change of state (i.e.
solid, liquid, or gas), or a phase transition.
38897.5 km3 of water evaporated annually = 38897.5 km3 /(365days X
24 hours X 60 minutes X 60 seconds) or .001233 km3/s
1000c.c of water = 1 kilogram
.001233 km3 of water = .001233 X 100,000 cm X 100,000 cm X
100,000 cm or .001233X1015 c.c. or 1.233 E+12 c.c. of water.
1.233 E+12 c.c of water = 1.233 E+12 / 1000 = 1.233E+9 kilograms
of water. Therefore 1.233E+9 kg/s could typically be evaporated
from the surface of the world’s irrigated hot deserts.
The heat required to evaporate this water would be taken up from
the desert and this heat can be calculated using the formula q =
hwe g, where q = heat supplied (kJ/s, kW) and hwe = 2270 (kJ/kg)
is the evaporation heat of water and g = amount of water
Therefore the amount of energy that would be taken up evaporating
water from the irrigated hot deserts (q) = (2270 kJ/kg) (1.233 E+9
kg/s) = 2.7989 E+12 kW
1 terra watt = 1 E+9 kw therefore roughly 2.7989 E+3 terra watts
of energy would be taken up evaporating water from the 10 largest
irrigated hot deserts of the world.
The purpose of an embodiment of the current invention is to
increase the surface area of the Earth subject to significant
evaporation, which in turn would contribute to cooling a warming
planet. As explained above the average annual evaporation in
deserts is roughly 2.5 m of water. Approximately this amount of
the water pumped into the desert for irrigation purposes would
therefore evaporate and would produce an added cooling influence
on a warming planet. As stated above deserts typically receive an
average annual precipitation of less than .25 m therefore the
cooling influence due to desert evaporation as a consequence of
the implementation of an embodiment of this invention would be at
least 10 times greater than the status quo.