var snowsrc="js/snow.png"
var no = 20;
 
var dx, xp, yp; // coordinate and position variables
var am, stx, sty; // amplitude and step variables
var i, doc_width = 800, doc_height = 600;
 
doc_width = document.body.scrollWidth;
doc_height = document.body.scrollHeight;
 
dx = new Array();
xp = new Array();
yp = new Array();
am = new Array();
stx = new Array();
sty = new Array();
 
for (i = 0; i < no; ++ i) {    
dx[i] = 0; // set coordinate variables
xp[i] = Math.random()*(doc_width-50); // set position variables
yp[i] = Math.random()*doc_height;
am[i] = Math.random()*20; // set amplitude variables
stx[i] = 0.02 + Math.random()/10; // set step variables
sty[i] = 0.7 + Math.random(); // set step variables
 
document.write("<div id='dot"+i+"' style='position:absolute; z-index: "+(100+i) +"; top:15px; left:15px;'><img src='"+snowsrc+"' border='0'><\/div>");
}
 
function snow() {    
for (i = 0; i < no; ++ i) { // iterate for every dot
yp[i] += sty[i];
if (yp[i] > doc_height-50) {
xp[i] = Math.random()*(doc_width-am[i]-30);
yp[i] = 0;
stx[i] = 0.02 + Math.random()/10;
sty[i] = 0.7 + Math.random();
}
doc_width = document.body.scrollWidth;
doc_height = document.body.scrollHeight;
dx[i] += stx[i];
document.getElementById("dot"+i).style.top = yp[i] + 'px';
document.getElementById("dot"+i).style.left = (xp[i] + am[i]*Math.sin(dx[i])) + 'px';
}
}
setInterval('snow()', 1);