// beteljuice.com - near enough Zambretti Algorhithm // June 2008 - v1.0 /* Negretti and Zambras 'slide rule' is supposed to be better than 90% accurate for a local forecast upto 12 hrs, it is most accurate in the temperate zones and about 09:00 hrs local solar time. I hope I have been able to 'tweak it' a little better ;-) This code is free to use and redistribute as long as NO CHARGE is EVER made for its use or output */ // ---- 'environment' variables ------------ var z_where = 1; // Northern = 1 or Southern = 2 hemisphere var z_baro_top = 1027; // upper limits of your local 'weather window' (1050.0 hPa for UK) var z_baro_bottom = 1007; // lower limits of your local 'weather window' (950.0 hPa for UK) // usage: forecast = betel_cast( z_hpa, z_month, z_wind, z_trend [, z_where] [, z_baro_top] [, z_baro_bottom]); // z_hpa is Sea Level Adjusted (Relative) barometer in hPa or mB // z_month is current month as a number between 1 to 12 // z_wind is English windrose cardinal eg. N, NNW, NW etc. // NB. if calm a 'nonsense' value should be sent as z_wind (direction) eg. 1 or calm ! // z_trend is barometer trend: 0 = no change, 1= rise, 2 = fall // z_where - OPTIONAL for posting with form // z_baro_top - OPTIONAL for posting with form // z_baro_bottom - OPTIONAL for posting with form // a short forecast text is returned var z_forecast = new Array("Estable, bueno", "Buen tiempo", "Volviendose bueno", "Bueno, volviendose menos estable", "Bueno, posibilidad de lluvias", "Bastante bueno, mejorando", "Bastante bueno, posibilidad de lluvias a primera hora", "Bastante bueno, lluvioso a ultima hora", "Lluvioso a primera hora, mejorando", "Cambiante, mejorando", "Bastante bueno, probabilidad de lluvia", "Bastante inestable, despejandose a ultima hora", "Inestable, probabilidad de mejorar", "Lluvioso, intervalos de sol", "Lluvioso, volviendose menos estable", "Cambiante, algo de lluvia", "Inestable, algunos interbalos buenos", "Inestable, lluvia a ultima hora", "Inestable, algunas lluvias", "Mayormente inestable", "Lluvia ocasional, empeorando", "Lluvia a ratos, muy inestable", "Lluvia frecuente", "Lluvia, muy inestable", "Tormentoso, puede mejorar", "Tormentoso, mucha lluvia"); // equivalents of Zambretti 'dial window' letters A - Z var rise_options = new Array(25,25,25,24,24,19,16,12,11,9,8,6,5,2,1,1,0,0,0,0,0,0) ; var steady_options = new Array(25,25,25,25,25,25,23,23,22,18,15,13,10,4,1,1,0,0,0,0,0,0) ; var fall_options = new Array(25,25,25,25,25,25,25,25,23,23,21,20,17,14,7,3,1,1,1,0,0,0) ; // ---- MAIN FUNCTION -------------------------------------------------- function betel_cast( z_hpa, z_month, z_wind, z_trend, z_hemisphere, z_upper, z_lower) { if(z_hemisphere) z_where = z_hemisphere; // used by input form if(z_upper) z_baro_top = z_upper; // used by input form if(z_lower) z_baro_bottom = z_lower; // used by input form z_range = z_baro_top - z_baro_bottom; z_constant = (z_range / 22).toFixed(3); z_season = (z_month >= 4 && z_month <= 9) ; // true if 'Summer' if (z_where == 1) { // North hemisphere if (z_wind == "N") { z_hpa += 6 / 100 * z_range ; } else if (z_wind == "NNE") { z_hpa += 5 / 100 * z_range ; } else if (z_wind == "NE") { // z_hpa += 4 ; z_hpa += 5 / 100 * z_range ; } else if (z_wind == "ENE") { z_hpa += 2 / 100 * z_range ; } else if (z_wind == "E") { z_hpa -= 0.5 / 100 * z_range ; } else if (z_wind == "ESE") { // z_hpa -= 3 ; z_hpa -= 2 / 100 * z_range ; } else if (z_wind == "SE") { z_hpa -= 5 / 100 * z_range ; } else if (z_wind == "SSE") { z_hpa -= 8.5 / 100 * z_range ; } else if (z_wind == "S") { // z_hpa -= 11 ; z_hpa -= 12 / 100 * z_range ; } else if (z_wind == "SSW") { z_hpa -= 10 / 100 * z_range ; // } else if (z_wind == "SW") { z_hpa -= 6 / 100 * z_range ; } else if (z_wind == "WSW") { z_hpa -= 4.5 / 100 * z_range ; // } else if (z_wind == "W") { z_hpa -= 3 / 100 * z_range ; } else if (z_wind == "WNW") { z_hpa -= 0.5 / 100 * z_range ; }else if (z_wind == "NW") { z_hpa += 1.5 / 100 * z_range ; } else if (z_wind == "NNW") { z_hpa += 3 / 100 * z_range ; } if (z_season == 1) { // if Summer if (z_trend == 1) { // rising z_hpa += 7 / 100 * z_range; } else if (z_trend == 2) { // falling z_hpa -= 7 / 100 * z_range; } } } else { // must be South hemisphere if (z_wind == "S") { z_hpa += 6 / 100 * z_range ; } else if (z_wind == "SSW") { z_hpa += 5 / 100 * z_range ; } else if (z_wind == "SW") { // z_hpa += 4 ; z_hpa += 5 / 100 * z_range ; } else if (z_wind == "WSW") { z_hpa += 2 / 100 * z_range ; } else if (z_wind == "W") { z_hpa -= 0.5 / 100 * z_range ; } else if (z_wind == "WNW") { // z_hpa -= 3 ; z_hpa -= 2 / 100 * z_range ; } else if (z_wind == "NW") { z_hpa -= 5 / 100 * z_range ; } else if (z_wind == "NNW") { z_hpa -= 8.5 / 100 * z_range ; } else if (z_wind == "N") { // z_hpa -= 11 ; z_hpa -= 12 / 100 * z_range ; } else if (z_wind == "NNE") { z_hpa -= 10 / 100 * z_range ; // } else if (z_wind == "NE") { z_hpa -= 6 / 100 * z_range ; } else if (z_wind == "ENE") { z_hpa -= 4.5 / 100 * z_range ; // } else if (z_wind == "E") { z_hpa -= 3 / 100 * z_range ; } else if (z_wind == "ESE") { z_hpa -= 0.5 / 100 * z_range ; }else if (z_wind == "SE") { z_hpa += 1.5 / 100 * z_range ; } else if (z_wind == "SSE") { z_hpa += 3 / 100 * z_range ; } if (z_season == 0) { // if Winter if (z_trend == 1) { // rising z_hpa += 7 / 100 * z_range; } else if (z_trend == 2) { // falling z_hpa -= 7 / 100 * z_range; } } } // END North / South if(z_hpa == z_baro_top) z_hpa = z_baro_top - 1; z_option = Math.floor((z_hpa - z_baro_bottom) / z_constant); z_output = ""; if(z_option < 0) { z_option = 0; z_output = "Tiempo excepcional, "; } if(z_option > 21) { z_option = 21; z_output = "Tiempo excepcional, "; } if (z_trend == 1) { // rising z_output += z_forecast[rise_options[z_option]] ; } else if (z_trend == 2) { // falling z_output += z_forecast[fall_options[z_option]] ; } else { // must be 'steady' z_output += z_forecast[steady_options[z_option]] ; } return z_output ; } // END function