1 /*****************************************************************************
3 Module: FGPhysicalProperties.cpp
4 Author: Christian Mayer
6 Called by: main program
8 -------- Copyright (C) 1999 Christian Mayer (fgfs@christianmayer.de) --------
10 This program is free software; you can redistribute it and/or modify it under
11 the terms of the GNU General Public License as published by the Free Software
12 Foundation; either version 2 of the License, or (at your option) any later
15 This program is distributed in the hope that it will be useful, but WITHOUT
16 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
17 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
20 You should have received a copy of the GNU General Public License along with
21 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
22 Place - Suite 330, Boston, MA 02111-1307, USA.
24 Further information about the GNU General Public License can also be found on
25 the world wide web at http://www.gnu.org.
27 FUNCTIONAL DESCRIPTION
28 ------------------------------------------------------------------------------
29 Initialice the FGPhysicalProperties struct to something sensible(?)
32 ------------------------------------------------------------------------------
33 29.05.1999 Christian Mayer Created
34 16.06.1999 Durk Talsma Portability for Linux
35 20.06.1999 Christian Mayer added lots of consts
36 11.10.1999 Christian Mayer changed set<> to map<> on Bernie Bright's
38 19.10.1999 Christian Mayer change to use PLIB's sg instead of Point[2/3]D
39 and lots of wee code cleaning
40 *****************************************************************************/
42 /****************************************************************************/
44 /****************************************************************************/
45 #include "FGPhysicalProperties.h"
46 #include "FGWeatherDefs.h"
48 #include "FGWeatherUtils.h"
50 /****************************************************************************/
51 /********************************** CODE ************************************/
52 /****************************************************************************/
53 FGPhysicalProperties::FGPhysicalProperties()
57 /************************************************************************/
58 /* This standart constructor fills the class with a standard weather */
59 /************************************************************************/
61 Wind[-1000.0] = FGWindItem(zero); //no Wind by default
62 Wind[10000.0] = FGWindItem(zero); //no Wind by default
64 Turbulence[-1000.0] = FGTurbulenceItem(zero); //no Turbulence by default
65 Turbulence[10000.0] = FGTurbulenceItem(zero); //no Turbulence by default
67 //Initialice with the CINA atmosphere
68 Temperature[ 0.0] = +15.0 + 273.16;
69 Temperature[11000.0] = -56.5 + 273.16;
70 Temperature[20000.0] = -56.5 + 273.16;
72 AirPressure = FGAirPressureItem(101325.0);
74 VaporPressure[-1000.0] = FG_WEATHER_DEFAULT_VAPORPRESSURE; //in Pa (I *only* accept SI!)
75 VaporPressure[10000.0] = FG_WEATHER_DEFAULT_VAPORPRESSURE; //in Pa (I *only* accept SI!)
77 //Clouds.insert(FGCloudItem()) => none
78 SnowRainIntensity = 0.0;
80 LightningProbability = 0.0;
83 unsigned int FGPhysicalProperties::getNumberOfCloudLayers(void) const
88 FGCloudItem FGPhysicalProperties::getCloudLayer(unsigned int nr) const
90 map<WeatherPrecision,FGCloudItem>::const_iterator CloudsIt = Clouds.begin();
92 //set the iterator to the 'nr'th entry
96 return CloudsIt->second;
99 ostream& operator<< ( ostream& out, const FGPhysicalProperties2D& p )
101 typedef map<FGPhysicalProperties::Altitude, FGWindItem >::const_iterator wind_iterator;
102 typedef map<FGPhysicalProperties::Altitude, FGTurbulenceItem>::const_iterator turbulence_iterator;
103 typedef map<FGPhysicalProperties::Altitude, WeatherPrecision>::const_iterator scalar_iterator;
105 out << "Position: (" << p.p[0] << ", " << p.p[1] << ", " << p.p[2] << ")\n";
107 out << "Stored Wind: ";
108 for (wind_iterator WindIt = p.Wind.begin();
109 WindIt != p.Wind.end();
111 out << "(" << WindIt->second.x() << ", " << WindIt->second.y() << ", " << WindIt->second.z() << ") m/s at (" << WindIt->first << ") m; ";
114 out << "Stored Turbulence: ";
115 for (turbulence_iterator TurbulenceIt = p.Turbulence.begin();
116 TurbulenceIt != p.Turbulence.end();
118 out << "(" << TurbulenceIt->second.x() << ", " << TurbulenceIt->second.y() << ", " << TurbulenceIt->second.z() << ") m/s at (" << TurbulenceIt->first << ") m; ";
121 out << "Stored Temperature: ";
122 for (scalar_iterator TemperatureIt = p.Temperature.begin();
123 TemperatureIt != p.Temperature.end();
125 out << Kelvin2Celsius(TemperatureIt->second) << " degC at " << TemperatureIt->first << "m; ";
128 out << "Stored AirPressure: ";
129 out << p.AirPressure.getValue()/100.0 << " hPa at " << 0.0 << "m; ";
132 out << "Stored VaporPressure: ";
133 for (scalar_iterator VaporPressureIt = p.VaporPressure.begin();
134 VaporPressureIt != p.VaporPressure.end();
136 out << VaporPressureIt->second/100.0 << " hPa at " << VaporPressureIt->first << "m; ";
143 inline double F(const WeatherPrecision factor, const WeatherPrecision a, const WeatherPrecision b, const WeatherPrecision r, const WeatherPrecision x)
145 const double c = 1.0 / (-b + a * r);
146 return factor * c * ( 1.0 / (r + x) + a * c * log(fabs((r + x) * (b + a * x))) );
149 WeatherPrecision FGPhysicalProperties::AirPressureAt(const WeatherPrecision x) const
151 const double rho0 = (AirPressure.getValue()*FG_WEATHER_DEFAULT_AIRDENSITY*FG_WEATHER_DEFAULT_TEMPERATURE)/(TemperatureAt(0)*FG_WEATHER_DEFAULT_AIRPRESSURE);
152 const double G = 6.673e-11; //Gravity; in m^3 kg^-1 s^-2
153 const double m = 5.977e24; //mass of the earth in kg
154 const double r = 6368e3; //radius of the earth in metres
155 const double factor = -(rho0 * TemperatureAt(0) * G * m) / AirPressure.getValue();
157 double a, b, FF = 0.0;
159 //ok, integrate from 0 to a now.
160 if (Temperature.size() < 2)
161 { //take care of the case that there aren't enough points
162 //actually this should be impossible...
164 if (Temperature.size() == 0)
166 cerr << "ERROR in FGPhysicalProperties: Air pressure at " << x << " metres altiude requested,\n";
167 cerr << " but there isn't enough data stored! No temperature is aviable!\n";
168 return FG_WEATHER_DEFAULT_AIRPRESSURE;
171 //ok, I've got only one point. So I'm assuming that that temperature is
172 //the same for all altitudes.
174 b = TemperatureAt(0);
175 FF += F(factor, a, b, r, x );
176 FF -= F(factor, a, b, r, 0.0);
179 { //I've got at least two entries now
181 //integrate 'backwards' by integrating the strip ]n,x] first, then ]n-1,n] ... to [0,n-m]
185 map<WeatherPrecision, WeatherPrecision>::const_iterator temp2 = Temperature.upper_bound(x);
186 map<WeatherPrecision, WeatherPrecision>::const_iterator temp1 = temp2; temp1--;
188 if (temp1->first == x)
189 { //ignore that interval
193 bool first_pass = true;
196 if (temp2 == Temperature.end())
198 //temp2 doesn't exist. So cheat by assuming that the slope is the
199 //same as between the two earlier temperatures
201 a = (temp2->second - temp1->second)/(temp2->first - temp1->first);
202 b = temp1->second - a * temp1->first;
207 a = (temp2->second - temp1->second)/(temp2->first - temp1->first);
208 b = temp1->second - a * temp1->first;
214 FF += F(factor, a, b, r, x);
219 FF += F(factor, a, b, r, temp2->first);
222 if (temp1->first>0.0)
224 FF -= F(factor, a, b, r, temp1->first);
229 FF -= F(factor, a, b, r, 0.0);
230 return AirPressure.getValue() * exp(FF);
235 { //ok x is smaller than 0.0, so do everything in reverse
236 map<WeatherPrecision, WeatherPrecision>::const_iterator temp2 = Temperature.upper_bound(x);
237 map<WeatherPrecision, WeatherPrecision>::const_iterator temp1 = temp2; temp1--;
239 bool first_pass = true;
242 if (temp2 == Temperature.begin())
244 //temp1 doesn't exist. So cheat by assuming that the slope is the
245 //same as between the two earlier temperatures
246 temp1 = Temperature.begin(); temp2++;
247 a = (temp2->second - temp1->second)/(temp2->first - temp1->first);
248 b = temp1->second - a * temp1->first;
253 a = (temp2->second - temp1->second)/(temp2->first - temp1->first);
254 b = temp1->second - a * temp1->first;
260 FF += F(factor, a, b, r, x);
265 FF += F(factor, a, b, r, temp2->first);
268 if (temp2->first<0.0)
270 FF -= F(factor, a, b, r, temp1->first);
272 if (temp2 == Temperature.begin())
274 temp1 = Temperature.begin(); temp2++;
283 FF -= F(factor, a, b, r, 0.0);
284 return AirPressure.getValue() * exp(FF);
290 return AirPressure.getValue() * exp(FF);