There 3
1. are numerous methods for determining reservoir evaporation using various measurements.
TIns p roblem assumes the water surface o f t he reservoir has an area o f 10 6 m 2 (1 k nl) w ith a steady
flow rate o f w ater into the reservoir o f 0 .2 m 3 S"I.
(a) The steady flow rate leaving the reservoir is 0.15 m 3 S"I . W hat is the daily evaporation rate i n
[lilin d ail]?
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= , 0 5m
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\ I"Y\."~ \ h (
vv;
3/
4 3 2 0 m 3/ ctaAf)
(b) The steady state dissolved salt concentration i n the flow entering the reservoir is 3 00 g m"3 a nd
the steady state dissolved salt concentratiOl1reaving t he reservoir is 400 g m"3. W hat is the daily
fi"\ t n C\.SS O lA-T
evaporation rate in [Iilin d ai'] ?
vV\tltSS
-=
QI C I
=Q2- C'2-
($DO~3) (O~ 1./Yl3/S) ~. Q2., L4EJo 9 jry, J)
Q 2 .:=' ( ). \ Sm3/ S
~.
tVr"'. as ~ft , c>c> -0v cq::;{) r C\th<J tI1 y e-v!e ,:s f N s =- )'0 ~ '13 t,.m t'h /rL J
( c) O ver a d ay the average heat input to the reservoir is 0 .125 k J m"2 S"1 and the enteriilfiiiici e xiting
water temperatures are the same. W hat is the daily evaporation rate in [ nml <l?-tl]?
Heak
In
HeOtt OlA- t
y
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4
2 . A vessel contains air and water vapor at 101.3 k Pa total pressure and a temperature o f 20C.
W ater is at its saturation vapor pressure o f P w = 2.34 kPa.
(_ _
a) What is
th ~ 1.
11aSS
1-
O ~O { 7~
\
ty)3
Q" l
oncent
,
o n o f w ater vapor in the vessel [g m-3 ]?
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o...
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--p~
n.}'V\ vJ -_ -,;-T M \Ai
V"..,
A
. -,
.
-- ---- -
I18 }G/ O~
2~..3...:.:...._ i)__ _-_ _ _ _ \
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~
(8 .1",'tJ/~.'~l ( z.,C{3 \V)
(b) D ry a ir has a molecular mass o f28 .97 g mole- 1 and water has molar molecular mass o f l8..z
m ole- J W hat is the total gas densit Y- at 1 01.3kP a total pressure ancl...2fC w ith water at its saturation
vapor pressure?
.
--------
(c) T he water-saturated air at 20C and 101.3 k Pa also has fog droplets (condensed liquid water)
dens ity-o the air calculated in part
f
with a mass concentration o f 0.06 g m -3 . WiTnliis fo g change 1 he ~
(b)?
/ + w ilt
[S
-=
----=-~- -
VV<)T
C~~ i+ b~
srq ~ f'n~t /
5
2 . (cont.)
(d) What heat is required to clear the fog [kJ m-3]?
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-r P'D~ y. (
;f
~~
\~~~) I~ ~ ' 'f--
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~ '$
150\Gj/~ ~
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6
3, Photosynthesis occurs within leaves with the overall reaction o f
CO 2 + H 2 0 = C H2 0 + O2
w here C H2 0 is a simplified fonnula organic for matter. The CO2 comes from the atmosphere and the
H 2 0 c omes ii-om the soil and the molecular oxygen, O2, is released to the atmosphere, The exchange
o f t he gaseous constituents occurs in a l eaf b oundary layer that is ofthiclmess b w h ere the air is
_
a ssumed to b e stagnant.
S h ~ J>t(a) Show b y a w ater mass balance over ~~~l1tial~ _J IQLvQ .!:llll e_t~~!~,:! er ~~ss c oncentration i
!
the air within the l eaf b oundary layer is described b y,
-.
~
P wa = D
2 P wa
-==-
a
w1eTe D wo
l
f-t"~ w~
aX'
1 1 d 'ffu "
t Ie m o eeli ar 1 S lVlty 0 w ater vapor III aI t.,-/>2l'
-
'1
IS
y __
a
~~\'~ ~$
OINt-
+-
AG-l.. -
--
-II.
--
Yi:-
/'
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. . .,
'i.-'lt>'/..
stea~
- f:>..f::;,
-----
'M.:}5!
7
)'r
\
\
\
I
)0
~
\ =~ c
" rAY
~ - -)t~ ~~) - Ffl{ )l) _ ~p_ \.-___-= ~(e~~:)
Ii
~
r (-===-- "\
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D- 7:
./? b
I~
~ ./ ./ I \ ...... \ 0 !Jw ofp
.; ...:::"
7:
F~~) X A ~ 1 ft = fjtr( x-rA>C)
pr,
I
~
~/
-. -
(b) What is the
state water mass concentration in air within l heJeafboundary l ayer i f t he
relative humidity is 100% at the l eaf s urf?-ce and P wn, b- in t h e-bulk -atmosphere?
/ \ Be(rpw"-~
(~) ?
o
? ' b=C,l<-~.
X
v
\@eO
X
p wt:).j
6
V
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Uti- .:ect~
of
( c) S un shines o n the dark leaves leading to a temperature of the leaf o f TL thai is gre qj:er J hal1Jhe
a mbient air temperature, Tnir , W hat is l he s teady state air temperature profile in the l eaf b oundary
layer?
- .~~ .
--
fSL
7
'. ~
3. (cont.)
(d) What is the expression for the heat flux magnitude and direction for the conditions in (c)?
- - - - -- - . .----------.
_.
(e) Sketch the approximate profiles o f CO2 and O2 in the leaf boundary layer when the leaf is actively
photosynthesizi ng.
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CO 't.---
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8
4. The dry atmosphere has an adiabatic lapse rate o f rd = - 1 ao lan-I .
e
(a) Sketch the temperature profile for a stabl~ dry atmospheric boundary layer compared to a neutral
atmospheric boundary layer.
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:::) V\ \( vJ'
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(b) What time o f the day would you expect to find a stable atmospheric boundary layer and why?
A+ hrqht J Ci\[1
CDvlS
o ff ~
Q ~J ~
(c ) Sketch the temperature pl~Qfi le for an unstable, dry atmospheric boundary layer compared to a
neutral atmospheric boundary 1<1Yer. _--._ . - -..
- - - - _... _ ___ ._
rrWJNtrv-t
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9
4. (cont.)
(d) What time o f the day would you expect to fmd an unstable atmospheric boundary layer and why?
lh ~
OJf~roooY' ) e"dr \'5
(,J-eur m
().(Lc{ y~):eg ~
~/ SW rrOvvruA
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y V\
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Ct:i ' .
( e) In respect for the weather today, describe mechanistically Santa Ana winds (also called Diablo
winds, Chinooks, fOlm)
/