Cloud Formation: Process

As the video discussed earlier, a block of air (called a parcel) containing water vapor rises from the heated surface. This process is known as convection. However, three other mechanisms form clouds.

• Orographic - Air is forced up along topographic barriers, such as mountains.
• Frontal - Less dense, warm air is forced to rise over cooler, denser air as a front moves through an area.
• Convergence - Air near the surface flows together and is pushed upward when it is squeezed together, like when two outflow boundaries collide.

With less pressure acting on the parcel, it begins to cool and expand. Once the parcel's temperature is equal to the dew point temperature, the water vapor condenses onto nuclei in the atmosphere, and a cloud will start to form.