Greetings -- The swirl was what came to my mind immediately upon seeing the contest name and brief. If I am correct, cold air comes down and hot air goes up, thus I tried to make them do that for each color and then have them "eddy" in the middle to create a combination of temperature. Thanks for the opportunity to contribute.
Greetings -- This time I just stretched it down and to the sides to look more horizontal. The third design I put with a black background because it's my belief that any color will stand out better on a dark background. Could be great for vehicle graphics (vinyl signage) and t-shirts and mugs.
Mr. Schneberger -- Thank you for the comments. When I first saw the posting for the contest the swirl was the first thing that came to mind. Then it was just a matter of configuring the blue and red lines so they were the same, one up and one down, the way air tends to travel depending on the temperature. Again, thanks for your comments.