Konstantinos

Hello all. I am trying to understand the difference between altitude and density altitude. The only difference is that density altitude depends on my position's current air temperature and altitude does not? If my position's current air temperature is increased, then the density altitude is also increased, but the altitude remains fixed. If my position's current air temperature is decreased, then the density altitude is also decreased, but the altitude remains fixed. I am right? According barometric formula of wikipedia (http://en.wikipedia.org/wiki/Atmospheric_pressure#Altitude_atmospheric_pressure_variation), the altitude depends on my position's current atmoshperic pressure, current seal level atmospheric pressure and current sea level temperature. According wikipedia (http://en.wikipedia.org/wiki/Density_altitude#Calculation), the density altitude depends on my position's current atmoshperic pressure, current seal level atmospheric pressure, current sea level temperature AND MY POSITION'S CURRENT AIR TEMPERATURE. Have I understood well? Also, I have created two scripts on matlab which calculate altitude and density altitude. Here are the codes and two simple running of them. Tell me your opinion: Altitude: fprintf ( 1,'Hello, I will calculate your altitude.\n' ); cslt=input('Please, give me the sea level temperature (degrees C):'); fprintf ( 1, 'Thank you.\n' ); cslap=input('Please, give me the sea level atmospheric pressure (mb):'); fprintf ( 1, 'Thank you.\n' ); cpsap=input('Please, give me the atmospheric pressure of your position (mb):'); fprintf ( 1, 'Thank you.\n' ); alt=8.31447*(cslt+273.15)*log(cslap/cpsap)/(9.80665*0.0289644); altf= alt*3.2808399; fprintf('Your altitude is %d m or %d feet\n', alt, altf); >> altitude Hello, I will calculate your altitude. Please, give me the sea level temperature (degrees C):17 Thank you. Please, give me the sea level atmospheric pressure (mb):1017.9 Thank you. Please, give me the atmospheric pressure of your position (mb):999.9 Thank you. Your altitude is 1.515332e+002 m or 4.971562e+002 feet >> Density Altitude: fprintf ( 1,'Hello, I will calculate your density altitude.\n' ); ts=input('Please, give me the sea level temperature (degrees C):'); fprintf ( 1, 'Thank you.\n' ); ps=input('Please, give me the sea level atmospheric pressure (mb):'); fprintf ( 1, 'Thank you.\n' ); tm=input('Please, give me the temperature of your position (degrees C):'); fprintf ( 1, 'Thank you.\n' ) pm=input('Please, give me the atmospheric pressure of your position (mb):'); fprintf ( 1, 'Thank you.\n' ); da=145442.156*(1-((pm/ps)/((tm+273.15)/(ts+273.15)))^0.234969); dam= da/3.2808399; fprintf('Your density altitude is %d m or %d feet\n', dam, da); >> Density_Altitude Hello, I will calculate your density altitude. Please, give me the sea level temperature (degrees C):17 Thank you. Please, give me the sea level atmospheric pressure (mb):1017.9 Thank you. Please, give me the temperature of your position (degrees C):23.5 Thank you. Please, give me the atmospheric pressure of your position (mb):999.9 Thank you. Your density altitude is 4.146678e+002 m or 1.360459e+003 feet >> Soon, I will buy a weather multimeter. Its instructions say: The DENSITY ALTITUDE screen is calculated from the absolute values of station pressure, relative humidity and temperature. And my mind is confused. Why it depends on relative humidity? What formula it uses? Thank you in advance.

We are descendants of Homo sapiens, aren't we? I want to ask you: What did Homo neanderthalensis and Homo erectus become of? Thank you.

Hello everyone. My name is Konstantinos and I am from Greece. I am studying Electrical and Computer Engineering at National Technical University of Athens and I just joined in this forum for discussing about sciences. My scientific interests are engineering, mathematics, physics, control systems engineering, robotics, astronomy, astrophysics, philosophy, meteorology, geography, technology, history, human evolution, medicine, biology, cloning, search of dinosaur, evolutionary history of life and too many others. I am looking forward to discussing with you about everything. Nice to meet you.