Physics Data - Freezing of Lakes and the Evolution of their Ice Cover - page 279

The solar zenith angle (Z)

cos Z ¼ sin / sin d þ cos / cos d cos s
sin d ¼ sin e sin ð j 80 2 p= 365 Þ

s ¼s GMT K= 15 þ D t

where / is the latitude, ʴ is the declination, ˄ is the local solar hour angle (zero at solar

noon), ʵ =23 ° 27' is the inclination of ecliptic, ˄ GMT is GMT (Greenwich Mean Time), K

is longitude, and t is time correction, | t| 30 min, available in astronomical tables.

Δ Δ \

4. Atmosphere

28.97 g mol - 1

Average molecular mass

Standard atmospheric pressure 1013.25 mbar = p 0

R a = 287.04 J kg - 1 ° C - 1

Gas constant of air

c p = 1.004 kJ kg - 1 ° C - 1 Specific heat of air (constant pressure)

2.4 · 10 - 2 Wm - 1 ° C - 1 Thermal conductivity (p 0, 0 ° C)

Density of dry air ˁ a = p a /(R a T ), p a - air pressure

1.293 kg m - 3 at 0 ° C and p a = p 0

Atmospheric transmissivity T tr ≈ 0.9

Dry air
Specific heat at constant pressure c p = 1004 J ° C - 1 kg - 1

c v = 717 J ° C - 1 kg - 1 Specific heat at constant volume

2.40 × 10 - 2 Jm - 1 ° C - 1 s - 1

Thermal conductivity (0 ° C)

The saturation water vapour pressures (mbar)
Over liquid water surface (ei) w ) and over ice surface (ei) i ) as functions of temperature ( ° C)

are given by

log 10 e w ð T Þ¼ 0 : 7859 þ 0 : 03477T

1 þ 0 : 00412T

ð T C Þ log 10 e i ð T Þ¼ log 10 e w ð T Þþ 0 : 00422T

The relation between speci c humidity (q) and water vapour pressure is

q ¼ 0 : 622e
p a

David R. Line, ed. (2001) CRC Handbook of Chemistry and Physics. 82nd edition
2001

2002. CRC Press 2001, Boca Raton, Fl.
Petrenko, V.F., and Whitworth, R.W. (1999) Physics of Ice. Oxford University Press.
Oxford, U.K.
Gill, A. (1982) Atmosphere

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Ocean Dynamics. Academic Press, London, U.K.

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