Environmental Engineering Reference
In-Depth Information
Figure 1.4 Earth as seen from space, NASA.
The cloud cover is evident and is a factor both in
the Albedo
condensation energy is estimated (see text) as
U
6 GM
E
=
10
32
J, which is
¼
0
:
R
E
¼
2
:
24
0.3 (the fraction of sunlight onto
the earth that is reflected) and in the trapping of
reradiated heat energy from the earth at 290 K
(greenhouse effect). The accurate spherical
shape comes from maximizing attractive
gravitational energy, which caused the
condensation of primordial dust into the
compact, initially molten, earth. The
equal to (
1) times the present rate of global
power usage times 5
10
11
years. The power in
the oceans
wave motions is estimated as
56 TW, see text. The radiation power
intercepting the earth from the sun is 174 PW,
which is 24.9MW per person, on a 24 h, 7 day
basis, counting 7 billion people.
greenhouse of temperature T
G
. So the modified energy balance is
4
4
4
p
R
E
s
SB
½ð
P
¼
T
E
Þ
ð
T
G
Þ
¼
121
:
8PW
;
ð
1
:
5
Þ
where we have taken the greenhouse temperature T
G
as 191.3 K, in a simple
analysis. According to Richter (op. cit., p. 13), the most important greenhouse gases
are CO
2
and water vapor [3].
1.1.1.2 An Introduction to Fusion Reactions on the Sun
In the simplest terms, the power density P
63MW/m
2
leaving the surface of the sun
comes fromnuclear fusion of protons, to create
4
He, in the core of the sun. Let us
nd
the total power radiated by the sun. This is 4
p
R
s
¼
10
26
W,
63
:
12 MW
¼
3
:
82
10
26
W is such a large value, do we
need fear the sun will soon be depleted? Fortunately, we can be reassured that the
lifetime of the sun is still going to be long, by estimating its loss of mass from the
10
6
km. This 3.82
making use of R
s
¼
0.696
