$( document ).ready(function() {
  
  count = 1;
  windowWidth = $(window).width();
  windowHeight = $(window).height();

  
  
  setInterval(function () {
    pos = Math.floor((Math.random() * windowWidth) + 1);
    delay = Math.floor((Math.random() * 100) + 1);
    
    $("body").append("<div style='left:"+pos+"px;' class='rain new' rel='"+count+"'></div>");
   
    setTimeout(function(){
      $( ".new" ).css("top",windowHeight).removeClass("new");

          
    },delay);
    
    
    count ++;
                          
  }, 1);
  

  
});