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114 lines
1.8 KiB
Perl
114 lines
1.8 KiB
Perl
#
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# Taupunkt.pm
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#
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# 2011-12-21 Michael Bussmann <support@mb-net.net>
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#
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package main;
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use strict;
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use warnings;
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use POSIX;
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sub
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Taupunkt_Initialize($$)
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{
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my ($hash) = @_;
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}
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#
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# calc_sdd(T)
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#
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# Sättigungsdampfdruck [hPa] ( Temperatur t [C] )
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# über ebenen Wasseroberflächen
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#
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# Nach Magnus-Formel
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#
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# E_w (t)= 6.112 hPa * e ^ (17.62*T / ( 243.12 °C + T))
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# für -45 °C <= t <= 60 °C
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#
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# Nach D.Sonntag (Wikipedia)
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# http://de.wikibooks.org/wiki/Tabellensammlung_Chemie/_Stoffdaten_Wasser
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#
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sub
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calc_sdd($)
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{
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my ($t) = @_;
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my $tk = $t+273.15;
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# Magnus
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#return ( 6.112 * exp( (17.62*$t)/(243.12+$t)) );
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# Wikipedia/D.Sonntag
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return ( exp( (-6094.4642/$tk) + 21.1249952 - ($tk*2.7245552e-2) + ($tk**2 * 1.6853396e-5 ) + ( 2.4575506*log($tk)) ) / 100 );
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}
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#
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# calc_dd(r, T)
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#
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# Dampfdruck [hPa] (rel. Feuchte r [%], Temperatur T [C] )
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#
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# DD = r/100 * sdd(T)
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#
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sub
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calc_dd($$)
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{
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my ($r, $t) = @_;
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return ( $r*calc_sdd($t)/100.0 );
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}
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#
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# calc_dewpoint(r, T)
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#
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# Taupunkt [C] (rel. Feuchte r [%], Temperatur T [C] )
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#
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# Taupunkt (ü.W.): a = 7.5, b = 237.3 (für T>=0)
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# Taupunkt (ü.W.): a = 7.6, b = 240.7 (für T<0)
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# Frostpunkt: a = 9.5, b = 265.5 (für T<0)
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#
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# TD(r,T) = b*v/(a-v) mit v(r,T) = log10(DD(r,T)/6.1078)
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#
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sub
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calc_dewpoint($$)
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{
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my ($r, $t) = @_;
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my ($a, $b, $v);
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if ($t>=0) {
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$a=7.5; $b=237.3;
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} else {
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$a=7.6; $b=240.7;
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}
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$v=log10(calc_dd($r, $t)/6.1078);
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return ( ($b*$v)/($a-$v) );
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}
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#
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# calc_af(r, T)
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#
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# Absolute Feuchte [g/m^3] (rel. Feuchte r [%], Temperatur T [C] )
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#
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# auf 1 bar (10^5 Pa)
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#
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# R* = 8314.3 J/(kmol*K)
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# mw = 18.016 kg
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#
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# AF(r,TK) = 10^5 * mw/R* * DD(r,T)/TK
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# AF(TD,TK) = 10^5 * mw/R* * SDD(TD)/TK
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#
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sub
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calc_af($$)
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{
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my ($r, $t) = @_;
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my $tk = $t+273.15;
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return ( (1801600/8314.3) * (calc_dd($r, $t)/$tk) );
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### return ( (1801600/8314.3) * (calc_sdd(calc_dewpoint($r, $t))/$tk) );
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}
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1;
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