dew_pont.c

DEW POINT CALCULATION ROUTINE

/* DEW_POINT.C */
 
#include <stdio.h>
#include <conio.h>

double func(double temp_,double rh_);

double calc_dewpoint(double h_,double t_);

double t    = 105.0;
double rh   = 50.0;

double dew_point_1 = 0.0;
double dew_point_2 = 0.0;
double dew_point_3 = 0.0;

#define a  17.1   //17.27  //
#define b 237.7   //237.7  //癈 

//******************************************

 main()
   {
    double h;
    for(t = 105.0;t <= 135;t += 5.0)
	 {
	  if(t == 135.0) t = 134.0;

// 1.
      dew_point_1 = (b * func(t,rh)) / (a-func(t,rh));   //NAJBOLJ TO菶N REZULTAT !

// 2.
      h = ((log10(rh)-2)/0.4343) + ((17.62*t)/(243.12+t));
	  dew_point_2 = 243.12*h/(17.62-h);	

// 3.	   
      dew_point_3 = calc_dewpoint(rh,t);
	  
	  printf("T=%6.1f Rh=%6.1f DP = %8.3f DP_2 = %8.3f DP_3 = %8.3f\n",t,rh,dew_point_1,dew_point_2,dew_point_3);
	 } 
	return;
   }

//******************************************
  
double func(double temp_,double rh_)
   {
    double result;
	result = ((a * temp_) / (b + temp_)) + log(rh_/100.0);
	return result;
   }
   
//******************************************

 double calc_dewpoint(double h_,double t_)
//--------------------------------------------------------------------
// calculates dew point
// input:   humidity [%RH], temperature [癈]
// output:  dew point [癈]
{ 
  double logEx,dew_point;
  logEx=0.66077+7.5*t_/(237.3+t_)+(log10(h_)-2);
  dew_point = (logEx - 0.66077)*237.3/(0.66077+7.5-logEx);
  return dew_point;
}

//******************************************