Hot, humid days are fast approaching, so I asked The Curl Whisperer to give us her expert opinion on how to cope:
It’s no surprise to find that weather plays a huge role in how our hair behaves on any given day. What most of us don’t know, however, is that humidity has little to do with how our hair acts and responds climate-wise. Believe it or not, there are times when the humidity can reach 100% and your hair will be dry, loose and in desperate need of additional moisture.
Sounds like a huge contradiction, doesn’t it? But for optimum curl behavior, the humidity is the last piece of weather information we need to make informed choices about our curl maintenance routine. Believe it or not, it’s not about the humidity–it’s actually all about the dew point.
The dew point is, simply put, the temperature to which the air must be cooled in order for it to reach total moisture saturation and any additional moisture must “leak” out of the air. Unlike humidity, it is the true measure of the amount of moisture in the air. For example: if the current air temperature is 69°F and the dew point is 57°F, condensation (and dew) will form if the air temperature is cooled down to 57°F because the air is then saturated with moisture and can’t hold any more.
And that’s when the relative humidity reaches 100%. Just because the relative humidity is 100%, however, doesn’t automatically mean you’ll have a bad hair day. That humidity figure isn’t an indication of how much moisture is in the air–how high the dew point is. The higher the dew point, the more moisture is in the air; conversely, the lower the dew point, the less moisture is in the air, because cold air cannot hold as much moisture as warm air can.
Think of it this way. Imagine a one-cup measure and a 10-gallon jug in front of you. Fill the one-cup measure completely to the top with water, then fill the 10-gallon jug about two-thirds of the way full. Now, the one-cup measure represents 100% humidity because the cup can’t hold any more moisture. But so what? If the air temperature is 38°F and the dew point is 38°F, there isn’t a lot of moisture in the air. The fact that the humidity is 100% doesn’t mean a thing because the cup just doesn’t hold that much water in the first place.
Now, the jug is a different story. Let’s say the air temperature is 86°F and the dew point is 72°F, relative humidity is 62%. Your first reaction on seeing the 62% humidity might be, “Hmmm, it’s not too humid today.” I guarantee you if you walk outdoors, however, you are going to feel like you ran right into a wall of wet, humid air. The air is just laden with moisture because the jug is capable of holding so much more of it, and that 72°F dew point tells us so.
What does this mean for us curly girls? It means once you start paying attention to the dew point instead of the relative humidity and observe how your hair reacts during low and high dew point days, you will then start to understand and anticipate how your hair will behave on any given day–and then you will instinctively know how to adjust your curl maintenance routine and product application accordingly.
Which is exactly where every naturally glamorous curly girl wants to be, I think 🙂
If you have a question for Tiffany, shoot me an email at firstname.lastname@example.org, using “Tiffany” as the subject line. We’ll pick one question per week.
More info on humidity and humectants– http://www.curlynikki.com/2009/06/curl-whisperer-on-humectants-and.html