Have you ever wondered why smoke from a cigarette or a vape tends to go out the car window? The answer lies in a phenomenon called the Venturi Effect. When your car is in motion, the air surrounding it speeds up, resulting in a decrease in pressure. This decrease in pressure is what causes the smoke to be drawn out of the window.
The Science Behind the Venturi Effect
The Venturi effect can be explained using the Bernoulli Equation, which is a conservation of energy equation for fluids. It states that the sum of the kinetic energy, potential energy, and pressure of a fluid remains constant along a streamline. In the case of the Venturi effect, the increase in the speed of the air flow around the car causes a decrease in pressure.
This decrease in pressure is similar to what happens when a chimney works better on windy days. The increase in the speed of the air flow creates a low-pressure area, which draws the smoke out of the car window.
It's important to note that the Venturi effect is more pronounced when the car is moving at higher speeds. At lower speeds, the effect may not be as noticeable.
Does Smoked Glass Provide UV Protection?
Many people believe that smoked glass in cars provides protection from harmful UV rays. However, this is a common misconception. Smoked glass, also known as privacy glass, is made by dying the inside of the glass to give it a darker hue. While it does provide privacy for the rear passengers, it does not block UV rays.
UV rays are a different spectrum of light than visible light, which is what privacy glass blocks. Therefore, even though privacy glass may impede the amount of visible light that enters the car, it does not offer any protection from UV rays.
UV rays can be divided into two types: UVA and UVB. UVA rays account for 95% of all UV light that reaches our skin and are known to cause damage to the skin, including an increased risk of skin cancer. UVB rays, on the other hand, are the leading cause of sunburn and also contribute to skin cancer. Both UVA and UVB rays can penetrate through privacy glass.
If you are concerned about protecting yourself and your passengers from UV rays, there are alternative options available. One option is to use window tints that specifically block UV rays. Another option is to use car sun shades, which can be easily applied to the windows to reduce UV exposure. Additionally, applying sun cream to the passengers' skin can also provide protection from UV light.
Window Tinting Laws and Regulations
It's important to be aware of the laws and regulations regarding window tinting on vehicles. In many countries, including the UK, there are specific rules regarding the amount of light that must be allowed through the front windscreen and front side windows.
In the UK, the law requires that at least 75% of light must be allowed through the front windscreen, and at least 70% of light must be allowed through the front side windows. These rules do not apply to the rear windscreen or rear passenger windows.
Driving with heavily tinted windows on the front side windows can result in enforcement action, such as a prohibition notice, a fixed penalty notice, or a court summons. It is also an offense to sell a vehicle with heavily tinted front windows.
While smoked glass in cars may provide privacy for the rear passengers, it does not offer any protection from UV rays. If you are concerned about protecting yourself and your passengers from UV exposure, it is recommended to use window tints that specifically block UV rays or to use car sun shades. It's important to be aware of the laws and regulations regarding window tinting in your country to avoid any enforcement action.
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