This article explores why ice cream melted faster than expected in front of a fan in the middle of summer, exploring the principles of heat transfer such as conduction, convection, and radiation to explain everyday scientific phenomena.
On a hot summer day, my sister took an ice cream cone from the convenience store in front of our house out of the freezer. It’s a blissful treat that makes me forget the heat for a moment. You sit in front of the TV, enjoy the cool breeze from the fan, and take a bite of ice cream, and for a moment, you forget about the cares of the world. But the joy doesn’t last long. The ice cream melts too quickly. Did I eat too slowly because I was watching TV? The sticky texture of the ice cream that has already dripped onto your hands and the floor makes you forget all about your brief but intense euphoria, and you feel betrayed.
Why did my ice cream melt so quickly? The reason why ice cream melts is not complicated. We all know that ice absorbs heat and turns into water, but how does the heat travel from the surrounding air to the ice cream, and what determines its speed? There are three ways heat travels: conduction, convection, and radiation. By looking at these methods, we can find out why the ice cream melted so quickly.
On a cold winter day, no one wants to sit on a bench outside in the park. That’s probably because we’ve all experienced that cold feeling. If you’re sitting on a cold bench and holding a hand warmer, your hands are warm, but your butt is cold. Your hand didn’t move, the hand warmer didn’t move. Similarly, your butt isn’t moving, and the chair isn’t moving. But heat does move, and this is called conduction. Conduction is the spreading of vibrations at the atomic or molecular level. A fast vibrating atom with a lot of energy collides with a slower vibrating atom right next to it and transfers energy, which is how we observe heat moving at the macroscopic level.
Convection uses the same principle of energy transfer by collisions at the molecular level, but the difference comes after the collision. Convection, as the name implies, is flow. While conduction does not change the relative positions of molecules after a collision between them, convection changes the relative positions of particles after the collision. In simple terms, for convection to occur, the substance transferring or receiving heat must be a gas or liquid, and on a macroscopic scale, the gas or liquid must be moving. For example, if you immerse your arm in stagnant water, conduction dominates; if you immerse your arm in running water, convection dominates. The rate at which heat travels is proportional to the temperature difference between the substances exchanging heat; if the temperature difference is the same, convection will move heat faster than conduction. This is why running water is often used as a first aid treatment for severe burns on hot objects.
You’ve probably seen the fire pillar special effects that are often used in martial arts, professional wrestling, and other sports when a fighter enters the ring, or when the atmosphere in a concert is electric. When the flames are blazing, you can feel your face heat up, even though there’s quite a bit of distance between where you’re sitting and the stage. But as soon as the flame disappears, my face cools down. This movement of heat cannot be explained by conduction or convection because the distance is not such that atoms or molecules can touch. This phenomenon is called radiation. Radiation is the transfer of heat by electromagnetic waves, such as light. All objects emit different types of electromagnetic waves at different intensities, depending on their temperature and surface condition, and at the same time they absorb the electromagnetic waves emitted by the objects around them. These electromagnetic waves contain energy, and heat is transferred based on the difference between the amount absorbed and the amount emitted. In the example above, heat is transferred to the face because the electromagnetic waves transmitted to the face from the pillar of fire have more energy than the electromagnetic waves emitted by the face.
Heat travels by conduction, convection, and radiation in a variety of ways, and it affects our lives in many ways. A pillar of fire, a burn first aid kit, or a cold bench are all examples of heat transfer. Based on the above methods of heat transfer, the reason my ice cream melted so quickly is probably due to the convection caused by the fan breeze. When there is no fan breeze, conduction dominates the heat transfer between the ice cream and the surrounding air, but when the wind blows, convection dominates. Therefore, the rate of heat transfer is faster and the ice cream melts faster. If I hadn’t been eating in front of the fan, my happy hour would have been uninterrupted. I’ll clean up first, and then text my sister to bring over some ice cream for tonight’s churros or scoops.
