You’ve passed Leona on your way to Dallas and my viewer from there sent me this email:
I live rural but near I45, probably about a mile east of the interstate near Leona.
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Why is it that sometimes the traffic sounds like it is right outside my door and sometimes I hear nothing at all. Also, sometimes it sounds like traffic is more north and sometimes more south. This really puzzles me and I’m wondering if it has to do with temperatures, wind or air pressure. These just doesn’t seem to be any consistency.
Perhaps this phenomenon is on one of you blogs?? Thanks and we’ll see you this evening!
Glen
Thanks for the note, Glen and the short answer is that the sounds you hear are about as consistent as the weather that occurs! First, the wind makes an absolute difference in that it carries sound with it, just like the leaves! Here’s a great illustration:
In fancy terms, this is called refraction, or the bending of sound waves either toward or away from the earth. The speed and direction of the wind changes the sound level. Consequently, sound levels are higher when the wind is blowing from the highway toward you (downwind). On the other hand, sound levels are lower when the wind is blowing away from you and toward the highway (upwind). So if the wind is headed in your direction, Glen, that highway is noisier!
In addition, sound is louder in cold temperatures and softer in warm temperatures. Temperatures change with height, cooling down, which is pretty common during the day. After all, warm air rises and cool air sinks. So during the day the warm air goes up causing sound waves to bend upward. Thus, sound levels go down.
At night, a warm layer of air above the cool night air can cause the sound waves to bend back toward earth. This is pretty common on Southeast Texas. Consequently, the traffic noise AT NIGHT may well be noisier than during the day, simply because the ground air has cooled, even though the traffic itself may be lighter!
By the way, sound travels at an average speed of 761mph. However, the lower the temperature, the slower sound travels. At 32° sound travels at 745mph while at 50° sound travels at 754mph. Sound travels 771mph at 74° and 786mph at 94°. So you are spot on with your thinking, Glen. Weather definitely plays a role in what you are hearing off I-45. I have the same issue with the Southwest Freeway, so I appreciate your question!
Thanks, Eclipse Watchers!
I don’t know if you bundled yourself up early this morning for the partial Lunar Eclipse, but several Click2pin fans did and I appreciate the photos. Here’s my favorite so far:
Super Santa Weather
One last note, Santa parachutes into Moody Gardens tomorrow between 4 and 6pm to give the Holiday Season a ‘jump’ start. Enjoy!
Have a wonderful weekend!
Frank