pilotak / meteofunctions

Collection of meteo fuctions

MeteoFunctions

Do you have your own meteo station based on Arduino or Mbed? and ever wondered how meteorologists get values like:

• Humidex
• Dew point
• Beaufort wind scale
• Wind chill
• Heat index
• Apparent temperature
• Cloud height base
• Relative pressure
• Absolute humidity

Let's add them to your project. You don't need any special sensors, it's just a math. Here is a class that do that for you. Supports both Celsius and Fahrenheit, please navigate to full example.

Arduino example

Please see examples folder

Mbed example

#include "mbed.h"
#include "MeteoFunctions.h"

MeteoFunctions calc;

float wind_speed = 2.0;   // m/s
float temp = 21.0;        // °C
float humidity = 60.0;    // %
float pressure = 975.8;   // hPa
float above_sea = 408.0;  // m

int main() {
    printf("Wind speed: %f km/h\n", calc.msToKmh(wind_speed));

    printf("Wind speed: %f m/h\n", calc.msToMph(wind_speed));

    printf("Wind speed: %f knots\n", calc.msToKn(wind_speed));

    printf("Beaufort wind scale: %u\n", calc.beaufort(wind_speed));

    printf("Humidex: %f *C\n", calc.humidex_c(temp, humidity));

    printf("Dew point: %f *C\n", calc.dewPoint_c(temp, humidity));

    printf("Wind chill: %f *C\n", calc.windChill_c(temp, wind_speed));

    printf("Heat index: %f *C\n", calc.heatIndex_c(temp, humidity));

    printf("Apparent temperature: %f *C\n", calc.apparentTemp_c(temp, humidity, wind_speed));

    printf("Could base: %f metres\n", calc.cloudBase_m(temp, humidity));

    printf("Relative pressure: %f hPa\n", calc.relativePressure_c(pressure, above_sea, temp));

    printf("Absolute humidity: %f g/m3\n", calc.absoluteHumidity_c(temp, humidity));

    return 0;
}

meteofunctions's Issues

Problem with humidex_f()

Thank you for taking the time to create and share MeteoFunctions.

I believe I've found one minor defect. In calls to humidex_f(), incorrect values are returned which are notably close to humidex_c() values. I believe converting the function result from celsius to fahrenheit yields the correct value as shown below.

/**

• Calculates humidex in Fahrenheit
  */
  float MeteoFunctions::humidex_f(float temp_f, float humidity) {
  return humidex_c(f_c(temp_f), humidity);
  }

/**

• REVISED to include addition of c_f()
  */
  float MeteoFunctions::humidex_f(float temp_f, float humidity) {
  return c_f(humidex_c(f_c(temp_f), humidity));
  }