The atmosphere — orography

How do hills and mountains affect the atmosphere?

Undulations on the surface of the Earth of any size and shape, from small hills to major mountain ranges that span continents, are known collectively as the orography of the Earth.

Orography affects the weather in a variety of ways, both on a local and global scale, including:

• enhancement of precipitation and increased wind speeds over mountain summits
• large-scale effects on the global circulation via a drag force exerted on the flow

Understanding and representing the effects of orography is crucial for weather forecasting and climate prediction since the phenomena usually occur on scales too small to be resolved by the computer models.

We are increasing our understanding through field and laboratory experiments and analytical and computer modelling studies.