Why is it called an "arch" ?

[Dieseldog]

Spent time searching here and Google but I cannot figure out why the evaporator is called an arch. My brother in Florida asked me, hence my search. Thanks for the help. Jim

[Urban Sugarmaker]

http://mapletrader.com/community/showthread.php?24560-Terms-of-the-trade&p=265794#post265794

[Dieseldog]

Thanks for the explanation. It does make sense too. Now I can get back to more important things to do on my Get Ready List. Jim

[3GoatHill]

Cool. Now I can sound like an expert. Even though I have no idea what I'm doing half of the time. :D