If you live in Canada, you know what a nightmare winter can be for your hair. No, it’s not because of the frizz on your hat (or at least not just because of the frizz on your hat), it’s because of static electricity! Big scarves and woolly hats can make your hair really frizzy. But even if you’re bald, you’ve probably noticed that you get more shocks in the winter when you reach for everyday objects like keys, doorknobs, and shopping carts. There’s some interesting science behind these seasonal shock scenarios and how to avoid them.
The main factor that affects the number of strikes is humidity. But to understand why, we first need to consider the concept of electricity. When two objects made of different materials touch, such as your hair and a hat, electrons are transferred between them. The longer the contact time, the more electrons are transferred, causing an imbalance of charge between your hair and the hat.
The movement of electrons from your hair to your hat or vice versa depends on what is called the triboelectric series. The triboelectric series essentially ranks different materials according to their propensity to lose or gain electrons. Some materials, like rubber or acrylic, easily gain electrons and become negatively charged. Other materials, like hair, glass, or wool, are more likely to lose electrons and become positively charged. In the case of your hair and wool hat, since human hair has a higher triboelectric series, electrons will flow from your hair to your hat.
The problem is that like charges repel each other, so now your hair is full of positive charges and quite unstable. That’s why when you get close to a conductive object, like a metal doorknob, the electrons from the doorknob can “jump” into your hair, neutralizing the charge and causing an electric shock. That’s why your hair stands on end when static electricity builds up on it. Hairs repel each other!
Why does charge build up on hair or clothing but not on other materials? Because insulating materials like plastic, fabric, or glass hold electrical charge very well, while conductive materials like metals do not.
Water is a great conductor, so in the spring, summer, and fall when Canada is humid, any negative charge that has built up on your body can easily transfer into the air (or from the air into your body, and either way, it can cause an electric shock). This happens all the time, we just don’t know it. But in the winter, when the air is drier, the charge sits on your skin, waiting to transfer to it when you get close to another conductor, like a car, a doorknob, or another person.
When we think about how humid or dry the air is, we tend to think only about humidity. But there’s another important number: the dew point. The dew point is the temperature at which the air is completely saturated with water. When the temperature is below the dew point, water condenses on solid surfaces, forming dew in the summer and frost in the winter (which is why the dew point can also be called the frost point). Warmer air can hold more moisture, which means that at lower temperatures, the dew point and the actual temperature are very close. Conversely, at higher temperatures, the difference between the dew point and the actual temperature is large.
Why is dew point important? Because temperature, dew point, and relative humidity (the percentage you see in weather apps) are closely related.
For example, at the time of writing this article, the outside temperature is -9 degrees Celsius and the relative humidity is 57%. Using the table below, or more precisely, this online calculator, we can determine that the dew point is -16 degrees Celsius. This tells us that if we go outside, we will not feel stuffy because the temperature is significantly higher than the dew point and the air is not saturated with moisture.
However, our furnaces blow this air into the house and heat it. This will not change the dew point, but it will change the temperature and relative humidity. The relative humidity was 57% at -16 degrees Celsius, but only 7% at 20 degrees Celsius. That’s really dry.
It is important to note that the only thing that changes here is the relative humidity. The absolute humidity remains constant because the furnace does not add or remove moisture when heating the air. So even if the air inside and outside are equally dry, it will feel drier indoors because of the relative humidity.
One of the easiest ways to protect yourself from the harsh Sahara Desert weather is to use a humidifier. Increasing the relative humidity in your home allows more charge to be released into the air, avoiding the shock of charge buildup. PS: If you think “desert-like” is too harsh a description of indoor conditions during a Canadian winter, think again. The average relative humidity in the Mojave Desert is 28%, which is 21% higher than where I currently live. No wonder my lips are chapped.
If a humidifier doesn’t help, you can also try swapping your rubber-soled flip-flops for leather-soled flip-flops. Since leather conducts electricity better than rubber, it prevents the charge from building up as much. Likewise, try wearing more cotton clothing. Cotton clothing is in the middle of the triboelectric series and doesn’t gain or lose electrons as easily, so it doesn’t build up charge like wool or fur.
Are you still worried about static electricity? From time to time, you can actively discharge static electricity. If you carry metal objects such as coins, keys, or paper clips and allow them to come into contact with metal objects in your home, the electrons attached to your body will pass through the metal, avoiding the “jumping” effect that causes static electricity.
Last but not least, you can always use an anti-static product to remove static from your hair and clothes. Hair dryer sheets contain chemicals like dipalmitoyl ethyl hydroxyethyl ammonium methyl sulfate, which when heated release positive ions, neutralizing the negative electrons on your clothes. You can even use dry hair paper to gently massage your hair and remove static! Anti-static sprays and anti-static guns can also be used to minimize static anywhere you need it, from your favorite clothes to your Rubber Soul vinyl records.