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In meteorology, latent heat flux is the flux of energy from the Earth's surface to the atmosphere that is associated with evaporation or transpiration of water at the surface and subsequent condensation of water vapor in the troposphere. It is an important component of Earth's surface energy budget.
Temperature-dependency of the heats of vaporization for water, methanol, benzene, and acetone. In thermodynamics, the enthalpy of vaporization (symbol ∆H vap), also known as the (latent) heat of vaporization or heat of evaporation, is the amount of energy that must be added to a liquid substance to transform a quantity of that substance into a gas.
Water vapor can also be indirect evidence supporting the presence of extraterrestrial liquid water in the case of some planetary mass objects. Water vapor, which reacts to temperature changes, is referred to as a 'feedback', because it amplifies the effect of forces that initially cause the warming. Therefore, it is a greenhouse gas. [2]
= latent heat of water vaporization, 2.45 [MJ kg −1], = specific heat of air at constant pressure, [MJ kg −1 °C −1], = ratio molecular weight of water vapor/dry air = 0.622. Both and are constants.
The latent internal energy of a system is the internal energy a system requires to undergo a phase transition. Its value is specific to the substance or mix of substances in question. The value can also vary with temperature and pressure. Generally speaking the value is different for the type of phase change being accomplished.
In atmospheric science, equivalent temperature is the temperature of air in a parcel from which all the water vapor has been extracted by an adiabatic process. Air contains water vapor that has been evaporated into it from liquid sources (lakes, sea, etc...). The energy needed to do that has been taken from the air.
A rising parcel of air containing water vapor, if it rises far enough, reaches its lifted condensation level: it becomes saturated with water vapor (see Clausius–Clapeyron relation). If the parcel of air continues to rise, water vapor condenses and releases its latent heat to the surrounding air, partially offsetting the adiabatic cooling.
As the moist air rises, it cools, causing some of the water vapor in the rising packet of air to condense. [21] When the moisture condenses, it releases energy known as latent heat of condensation which allows the rising packet of air to cool less than its surrounding air, [22] continuing the cloud's ascension.