Вот код 
function Pict () {
	var date = new Date();
	var vr;
	 if(date.getHours() >= 5 & date.getHours() < 12)
   {
   	vr = 'utro.jpg';
   }
   else if(date.getHours() >= 12 & date.getHours() < 18)
   {
   	vr = 'deni.jpg';
   }
   else if(date.getHours() >= 18 & date.getHours() < 0)
   {
   	vr = 'vecher.jpg';
   }
   else if(date.getHours() >= 0 & date.getHours() < 5)
   {
   	vr = 'noch.jpg';
   }
   document.getElementById("hor").innerHTML='<img src="' + vr + '" class="den">';
};
setTimeout(Pict, 1000);
setInterval(Pict, 1000*60);