// beteljuice.com - near enough Zambretti Algorhithm 
// June 2008 - v1.0
// tweak added so decision # can be output

/* 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 = 1050;	// upper limits of your local 'weather window' (1050.0 hPa for UK)
var z_baro_bottom = 950;	// 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])[0];

// 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
// [0] a short forecast text is returned
// [1] zambretti severity number (0 - 25) is returned ie. betel_cast() returns a two deep array

var z_forecast = new Array("Vreme stabila", "Vreme frumoasa", "Devine mai bun", "Devine instabila", "Mai pužin stabila", "Se amelioreaza", "Destul de buna, posibil la īnceputul zilei sć vinć lapovita", "Destul de buna, mai tīrziu ploios", "Ploios devreme, se īmbunatateste", "Schimbatoare", "Destul de buna, prosibil dusuri", "Mai īnorat, ameliorarea mai tīrziu", "Inchisa, probabil se īmbunatateste", "Ploios, cu intervale īnsorite", "Ploios, devenine mai pužin stabila", "Schimbatoare, ploi scurte", "Inchisa, cu intervale bune scurte", "Inchisa, ploi mai tīrziu","Foarte īnchisa", "Ploi ocazionale, spre īnrautatire", "Ploi din cīnd īn cīnd, foarte īnchisa", "Ploi frecvente, la intervale", "Ploi, foarte īnchisa", "Furtunoasa, dar se īmbunateaste", "Furtunosa, dar putine ploi"); 

// 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) ; 

var z_test = new Array();

// ---- 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 = "Vreme rece, ";
	}
	if(z_option > 21) {
		z_option = 21;
		z_output = "Vreme calda, ";
	}

	if (z_trend == 1) { 	// rising
		z_output += z_forecast[rise_options[z_option]] ; 
z_test[1] = rise_options[z_option];
	} else if (z_trend == 2) { 	// falling
		z_output += z_forecast[fall_options[z_option]] ; 
z_test[1] = fall_options[z_option];
	} else { 	// must be 'steady'
		z_output += z_forecast[steady_options[z_option]] ; 
z_test[1] = steady_options[z_option];
	} 
//	return z_output ; 
z_test[0] = z_output ;
return z_test ; 
}	// END function