Carolina Global Warming - Manual (Page 4)

18
GLOBAL WARMING
The drops will keep growing if you take
the light away and let the dome cool.
When the drops are large enough, they
will run down the sides of the dome.
Taste the water of condensation. Is it
still salty? If your experiment were to
run long enough, all the water would
evaporate and the salt would remain
behind in the petri dish. This technique
can be used in an emergency to make
drinking water out of seawater. How-
ever, the evaporated and condensed
water would lack important minerals.
Explanation:
Only pure water evaporates from the
oceans, leaving the salt behind. The
water condenses in the air and collects
into larger droplets, which eventually
rain down again as fresh water. That is
why rainwater is never salty, even near
the ocean.
Evaporation does not only occur above
bodies of water. Evaporation also takes
place over land, from water stored in
the ground and, above all, in plants.
That is why you have to water the gar-
den so often in summer when tempera-
tures are high.
Clouds collect on the Sierra Nevada.
DID YOU KNOW ? DID YOU KNOW ?
It’s Raining...
The distribution of land and water
masses over the Earth largely de-
termines where rain falls. Rainfall is
also influenced by large mountain
ranges and plains, and by air pres-
sure regions. In the interior areas of
the continents, dry climates prevail
with cold winter months and nights
and hot summer months and days.
Maritime climates determine the
weather on the coasts, with mild
winters and cool summers. Desert
climates generally prevail over large
land masses bordered by mountain
ranges against which clouds release
their rain. For example, the high
Sierra Nevada mountain range in
California catches the rain from the
moist Pacific Ocean air as it flows
eastward. On the ocean side of the
range, you will find thick forests and
fertile valleys. On the other side, to
the east, is where the hot California
desert begins.
Clouds form
Dry
Wet
Precipit
ation
Do
wndr
aft
Updr
af
t
Clouds
break up
Global Warming Manual Inside.indd 18 4/13/09 8:22:20 PM