It is not a homework,but this is my question and I hope sb to explain it for me:
There is not snow is the area I am living, but in the winter, sometimes I see the ice on my car. I notice that the water is ALWAYS iced at the positions: roof-rack. the lid of the trunk, hood , and windshied. I never see the ice on the different positions even though I park my car in any direction. I don't understand what caused that phenomenon.
Please explain for me. Thank you.
You are very observant and have asked an interesting question. The parts of the car that you mentioned have low heat capacity (and thus are easier to cool) and face mainly upward. On a clear night, even if the air temperatures are above freezing, upward-facing surfaces radiate away their heat more quickly to the cloudless sky, and can cool below the freezing point.
Your car probably has a slanted windshield, for better aerodynamics. Much older cars with vertical windshields (and side windows) are less likely to get iced up because they "see" less of the open sky. The ice comes from water vapor in the air, condensing on the below-freezing surface.
Thanh you drwls
The phenomenon you're observing, where the water on your car always freezes at specific positions such as the roof-rack, lid of the trunk, hood, and windshield, can be explained by a combination of factors including temperature, airflow, and surface properties.
1. Temperature: Different parts of your car have varying exposure to the surrounding temperature. For example, the roof-rack, trunk lid, hood, and windshield are all exposed to the open air and tend to cool down more quickly. This means that when moisture or condensation forms on these surfaces, they can reach freezing temperatures faster than other parts of your car.
2. Airflow: The movement of air around your car can play a role in freezing water at specific positions. As your car moves, air flows over its surfaces, and this airflow can affect the rate of heat transfer. Areas where airflow is restricted or stagnant, such as the roof-rack, lid of the trunk, and hood, may experience slower heat dissipation, allowing the water to linger and freeze.
3. Surface properties: The materials and properties of different car surfaces can influence how water freezes. Some surfaces may have higher heat conductivity, causing them to dissipate heat more easily and prevent the water from freezing. Others may have lower heat conductivity, retaining heat and allowing the water to freeze faster.
To further investigate this phenomenon, you can try experimenting with different parking orientations, such as parking your car in a different direction or in areas with varying wind conditions. This may help you identify correlations between specific airflow patterns and the formation of ice on your car.
Remember, the above explanation is based on general principles, and the specific details may vary depending on your car's design, construction materials, and local weather conditions.