Katabatic winds develop at night when there are clear skies, a general slack Anabatic winds occur in the Alps in summer months when there is generally a. Anabatic wind. related topics. Katabatic wind · Local wind system. Anabatic wind, also called upslope wind, local air current that blows up a hill or mountain. Katabatic is a local wind caused (often at night) by the flow of air, cooled by radiation, down mountain slopes and valleys. It is also caused by.
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What Causes Surface Winds, Mountain Winds and Anabatic Winds
Temperature, wind and rainfall are all heavily influenced by these geographical wonders, to the extent that mountain ranges can impact the climate of vast areas. The aabatic mountains have on rainfall is one of the most significant.
When moist air moves over mountains it is forced upwards, causing a rapid fall in temperature which condenses the moisture. This creates clouds and rainfall where there was none called orographic rainor adds to existing weather systems to intensify rainfall similarly called orographic enhancement. As the same air crests a mountain peak, it descends potentially much drier because much of the moisture has already been rained or snowed out.
Thus we see a classic pattern where one side of a mountain katabatuc the side from which weather typically approaches will be particularly wet while the other will be particularly dry. We see that anabxtic in the UK, with western areas such as the Lake District being much wetter than areas to the east. In North Anabaic, east of the Rockies, the Chinook wind is a powerful example of the Foehn phenomenon, known for its ability to “eat snow”.
In the UK the impact isn’t quite as large, but eastern areas such as Aberdeen can be significantly warmer than areas to the west of high ground. There are two other key types of wind influenced by mountains: Anabatic winds happen typically when the land is strongly warmed by sunshine. As the lowest layers of the air over the sunny slopes are warmed by the land, a current is set up which flows up the mountain.
Katabatic winds happen when cold air on top of a mountain or glacier descends because it is denser than milder air lower down. Gravity sees that cold air accelerate down the mountain to the point where, in extreme places like Antarctica, these winds can reach hurricane force.
They are generally cold for obvious reasons, but can be warmed if they flow over hotter surfaces on their way down – the Santa Ana wind in California is one example. There’s an even bigger factor to talk about when it comes to mountain weather – temperature. We think of mountains as cold, often snow-covered, environments – but why are they like this and do we ever see exceptions?
Let’s start with the basic physics. Due to the interaction between gravity, pressure and temperature when the air is mixed in the vertical, you normally expect the atmosphere to get colder as you ascend – this is called the adiabatic lapse rate of temperature with height. The adiabatic lapse is easy to remember in dry air: The temperature difference will be less in moist air, which we see a lot of in the UK, so we can’t always rely on that formula to be exact.
That said, you can expect that most of the time you will see a significant fall in temperature as you ascend – particularly when you include the impacts of more wind exposure increasing wind chill. However, sometimes the vertical temperature gradient can be turned on its head, leading to what we call a temperature inversion – which means sometimes it will get warmer as you ascend. This happens when the air at ground level is colder than the air above and there are two potential causes for this.
Firstly, warm air can move in over colder air – because the colder air below is denser, it becomes trapped there. The second cause is when the ground cools rapidly, cooling the atmosphere from the ground up while the air above remains milder.
This typically happens on clear, still nights, as the ground rapidly radiates its stored heat. Both these causes of inversion trap cooler air below, which often leads to misty or foggy conditions.
It can also mean clouds form and are trapped at lower levels. This means you can ascend through cloud to break through into the sunshine and have beautiful views of the cloud below – making any surrounding peaks look like islands in the mist. Clearly this pleasant inversion scenario doesn’t happen all that often, so it’s safer to expect conditions to be colder up the mountain than down.
Also, while inversions do mean it can get milder as you ascend, mountain weather can always change quickly so it’s always advisable to pack your usual warm and waterproof layers just in case. If you are interested in clouds or thunderstorms, UK climate or weather extremes, this series of factsheets clearly describes and illustrates the processes involved.
When water is heated, it evaporates and turns into water vapour which rises into the air.
Anabatic wind – AMS Glossary
The air cools and the vapour condenses into water droplets which eventually become so large they fall from clouds back to Earth. Wind chill factor takes into account wind speeds and humidity to assess how the human body actually feels temperature. Snow forms when tiny ice crystals in clouds stick together to become snowflakes. If enough crystals stick together, they’ll become heavy enough to fall to the ground. Products Mountain Mountain Weather.
We’ve brought you back to the current site. Related pages Met Office mountain widget Factsheets If you are interested in clouds or thunderstorms, UK climate or weather extremes, this series of factsheets clearly describes and illustrates the processes involved.
Why does it rain? Wind chill factor Wind chill factor takes into account wind speeds and humidity to assess how the human body ansbatic feels temperature. Where are the windiest parts of the UK? Find out more about the UK’s windiest places.
Snow Snow forms when tiny ice crystals in clouds stick together to become snowflakes. Get updates Email alerts RSS.