<script>
var t = setInterval(
function(){
var documentHeight  = $(document).height();
var startPositionLeft  = Math.random() * $(document).width() - 100;
var startOpacity = 0.5 + Math.random();
var sizeFlake = 10 + Math.random() * 20;
var endPositionTop = documentHeight - 40;
var endPositionLeft = startPositionLeft - 100 + Math.random() * 200;
var durationFall = documentHeight * 10 + Math.random() * 5000;
$('#flake')
.clone()
.appendTo('body')
.css(
{
left: startPositionLeft,
opacity: startOpacity,
'font-size': sizeFlake
}

)
.animate(
{
top: endPositionTop,
left: endPositionLeft,
opacity: 0.2
},
durationFall,
'linear',
function() {
$(this).remove()
}
);
}, 500);

var snow = {};
var snowflex = {};
snowflex.create  = function(){
var flex = document.createElement('div');
flex.innerHTML   = "❄";
flex.style.fontSize  = 10 + Math.random() * 20 + 'px';
flex.style.top  = - 50 + Math.random() * 20 + 'px';
flex.style.left  = Math.random() * 1500 + 'px';
flex.style.position  = "absolute";
flex.style.color  = "#F3F3F3";
flex.style.opacity = Math.random();
document.getElementsByTagName('body')[0].appendChild(flex);
return flex;
};

snow.snowflex = function(){
var flex = snowflex.create();
var x = -1 + Math.random() * 2;
var t = setInterval(
function(){
flex.style.top  = parseInt(flex.style.top) +  5 + 'px';
flex.style.left = parseInt(flex.style.left) +  x + 'px';
if (parseInt(flex.style.top) > 1500) {
clearInterval(t);
document.getElementsByTagName('body')[0].removeChild(flex);
}
}, 45 + Math.random() * 20);
};

snow.storm = function(){
var t = setInterval(
function(){
snow.snowflex();
}, 500);
};

//snow.storm();

var fog = {};
fog.draw = function(ctx, x, y){
ctx.fillStyle = "rgba( 255, 255, 255, " + Math.random() + " )";
ctx.arc( x, y, 10,0,Math.PI*2,true);
ctx.closePath();
ctx.fill();
};

fog.start = function(){
var ctx = document.getElementById('canvas').getContext("2d");
var x = 0;
var y = 0;
var t = setInterval(
function(){
x = 300 + 300*Math.sin(x);
y = 300 + 300* -Math.cos(x);
x += 2;
fog.draw(ctx, x, y);
}, 100);
};

//fog.start();
</script>