var date = new Date();
var hours = date.getHours();
if ( (hours >= 6) && (hours < 18) )
document.write('<img height="160" width="236" src="images/tampa_am.jpg" border="0" alt="Tampa - Day">');
else
document.write('<img height="160" width="236" src="images/tampa_pm.jpg" border="0" alt="Tampa - Night">');