The Orographic rain Occurs when humid air is pushed from the sea to a mountain by an ascending slope.
Orographic rain is the nucleus of the interaction between the earth's surface and the atmosphere. Not only is it important for the conservation of ecosystems of nature and natural resources, such as water for humans, but it is also important for other physical components of the terrestrial system.
For example, floods, landslides and avalanches are affected by the intensity of rainfall in fairly mountainous areas.
As the air rises and cools, orographic clouds form and serve as a source of precipitation, that is, rain.
The clouds condense into water vapor and form clusters. These can produce both rain and heavy thunderstorms.
When airflow is interrupted by a hill or mountain and is forced to rise, it can cause changes in the weather system.
The rise of humid air on the ground is not enough for precipitation to occur, this occurs when there are already storms in the environment.
On the other hand, when the descending air heats up and dries, both the cloud and the precipitation evaporate.
When the air descends on the leeward side (opposite place from where the wind comes), it has lost most of its moisture due to rain.
In this case the precipitation is usually low and the area is said to be in a rain shadow.
Places where more orographic rain occurs
Some places in the world such as the islands of Hawaii and New Zealand are known to have abundant orographic rainfall.
In these islands, most of the precipitation is on the windward sides (from where the wind comes) and the opposite places remain relatively dry.
However, this phenomenon gives rise to some discrepancies. For example, the coast receives less rain than places with higher altitudes and leeward things are generally dry. That said, Hawaii receives less rainfall a year than the highlands like Wai'ale'ale in Kaua'i.
Another place that is known for its orographic rainfall is the Pennine mountain range in the north of England.
In the west of this mountain range, Manchester has more rain than Leeds, located in the east. This city has less rain because the precipitation is lower, in other words, it is in the rain shadow area.
This type of rain plays an important role in the type, intensity and duration of precipitation.
Studies have shown that the width of the earth barrier, the inclination and the speed at which the air moves upwards, define the amount and intensity of orographic rainfall.
References
- Abuwala, A. (2017). What Is Orographic Precipitation? Recovered from:
- Worldatlas.comMinder, Justin R. and Roe, Gerard, H. (s.f.). Orographic precipitation. Recovered from:
- Earthweb.ess.washington.eduRoe, Gerard H. (2005). Orographic precipitation. Annual Review of Earth and Planetary Sciences, 33. Retrieved from:
- Earthweb.ess.washington.eduThe Editors of the Encyclopaedia Britannica. (2017). Orographic precipitation. Recovered from: Britannica.com.