My research is to use wind trajectories to find pollutant sources in Chicago. How do I translate longitude and latitude into the exact location, say Sears Tower or United Center?

First of all, the meteorological data used in our models are not “fine” enough to distinguish the difference between two locations in the city of Chicago. The ARL archive dataset that has the best resolution in that region is the EDAS archive, which was saved at a horizontal resolution of about 80 km (prior to January 2004, thereafter it is 40 km). So, anything that you are trying to resolve less than 80 km (or 40 km) apart is not feasable with our system. To find the latitude/longitude for your location just look in an atlas for the city of Chicago and find the latitude and longitude lines that intersect that area, or choose the nearest National Weather Service Station, which is probably Chicago Ohare (ORD) and enter it on the HYSPLIT input page.