It's summer time, which means it's time for ice cold drinks. But have you ever noticed that when you put a cold beverage into a glass or cup, it starts to sweat? Why does this happen? This phenomenon has to do with the way heat energy moves from one object to another.
It's called condensation. It's caused by a difference in temperature between two objects. When you take a cold cup and put it on your warm hand, the water molecules in both your skin and inside the cup begin to evaporate (the process of changing from liquid to gas). As they evaporate, they absorb energy from their surroundings, causing them to collide with other air molecules around them. This collision creates more heat energy which results in some of these water molecules turning back into liquid form! Those that don't turn back into liquid form will move away from each other until they find another surface that is cooler than themselves—like your hand or table—where they will stick once again as droplets of water!
When you add water to ice cubes, the resulting mass of ice and water is a lower temperature than when it was just plain old ice. The reason for this is that adding heat energy to a substance causes its molecules to move faster and become more random in their motion. This makes them spread out more evenly throughout their container, lowering the average kinetic energy (energy of motion) of those molecules. So by adding water, you have slowed down some aspects of your drink's molecular movement—slowing down not only melting but also evaporation!
Let's start with sweat, because the word is used to describe both the water that comes out of your pores and the moisture that collects on a cup or cold beverage. The latter is actually a type of condensation—the process by which water vapor in the air turns into liquid when it comes into contact with an object that's colder than its surroundings. That's why you've probably noticed moisture droplets gathering on the outside of a glass of ice water, and it's where we get the word “condensation”: condensing from gas to liquid.
In this case, we can think of your sweaty pore as being like an atmospheric layer—a pocket where air pressure changes quickly enough for water molecules (and other gases) inside it to turn into liquids or solids without having time to dissolve back into gas before reaching their destination. Because our bodies are warm compared to most objects around us, they're typically covered in many tiny little atmospheric layers—cells full of hot stuff surrounded by cooler stuff—but only some will have enough moisture content inside them for droplets to form at our skin's surface when they come together with something colder than them outside those cells' walls.
When you place a cold glass in a warm environment, the air temperature around it is warmer than the temperature of the glass itself. As we've learned earlier, when two objects have different temperatures, they transfer heat across their boundary by convection (molecules moving from one side to another) or radiation (electromagnetic waves). In this case, when you put your cold drink into a room-temperature environment full of warm molecules, they start to move faster than they were before. They collide with each other and transfer some energy to their neighbors—which happen to be those on your cup or glass!
So why does this happen? How can something that's not moving at all get hot when there's no friction involved?
Condensation is all around us, even on the insides of our homes. When you go to the bathroom in wintertime and see little puddles of water on your windows, those are condensation droplets. So it’s not just something that happens when you put something cold into a hot glass (or vice versa)—it happens all over our planet!