What is Condensation? — Definition & Examples
Condensation definition
Condensation is the phase change in the state of matter from gas to liquid. Condensation is the opposite of evaporation (liquid becomes gas).
The condensation process can occur with any substance that vaporizes at workable temperatures, such as water, alcohols used in distilling, and hydrocarbons used in petroleum refining.
When does condensation occur?
Condensation occurs when the atmosphere will hold no more water vapor; this is the saturation vapor pressure. The higher the air temperature, the higher the saturation vapor pressure. This is why warmer climates have higher relative humidity than cooler climates—the warmer air can hold more water.
The higher the atmospheric vapor pressure, the more water vapor is already in the air. Vapor pressure in meteorology (weather studies) is the pressure exerted by water molecules in the air.
Condensation point of water
The condensation point of water is the temperature at which water vapor loses enough thermal energy to change into liquid form again. This is also the boiling point of water at sea level. At (), freshwater becomes water vapor, the gaseous form of liquid water.
The point of condensation for atmospheric water is also referred to as the dew point. The dew point temperature varies according to pressure and humidity.
When warm air full of water vapor cools to its dew point by contacting something with a colder surface temperature, the gaseous water will condense, causing water droplets to form on the surface of the object.
Condensation process
When we see a chilled glass of a beverage “sweat” with water droplets on a hot day, we know the glass and air are not at . Enough water molecules in the water vapor of the air are losing energy, though, to change phase from gas to liquid. This causes condensation to form at the surface of the cold glass, chilled by the ice cubes and cold beverage.
Any gaseous substance will condense when pressure and temperature allow the particles to lose thermal energy and move closer together.
Water vapor does this when it comes in contact with the colder glass. Thermal energy moves from the water molecules in the air onto the chilled glass, the water molecules slow down and move closer, and they change from gas to liquid.
The greater the temperature difference between the cold surface and the warmer gas, the faster and greater the condensation rate. This is the same process as a steamy shower fogging up the bathroom mirror.
Condensation examples
Jets leave contrails or condensation trails. These are lines of pure water and ice exhausted from the jet's engines. As warm water vapor leaves the hot engines, it condenses rapidly in the cold air, leaving white streaks.
Distilling depends on condensation. Distilleries produce alcoholic spirits (whiskey, rum, brandy, and beer) by heating closed containers of fermented materials (barley, hops, rye, and other grains, fruits, or vegetables) until the alcohol vaporizes and condensation forms against the cool surface of the metal at the top of the container. This is drawn off through metal coils chilling in water.
Distillation can also be used in science laboratories to produce useful items like rubbing alcohol, herbs, spices, and food flavorings (especially from citrus fruits). Distilled water, perfume, and petroleum products are also made using the same methods.
Condensation is a critical part of the water cycle, as it is responsible for cloud formation. Water vapor combines with particles of dust, salt, and smoke to create cloud droplets, which develop into clouds high in the sky where there is cooler air. When a cloud becomes too saturated, the water will return to the Earth’s surface in the form of raindrops or other precipitation.
Air conditioning and dehumidifiers use condensation to remove water vapor from the air, making indoor air more comfortable.