All of these scenarios for how weather systems evolve over the United Kingdom differ from the classic rain shadow with a uniform steady westerly flow impinging on the Peak District and wringing moisture out during orographic ascent, leaving drying in its lee.
To test the possible occurrence of a rain shadow, we perform three tests.
For this analysis, we define a rain shadow as a day where it rained on the windward-side stations, but not on the leeward-side stations.
Specifically, westerly winds were more likely to produce precipitation than easterly winds (75% vs 46%), westerly winds were more likely to exhibit a rain shadow than easterly winds (17% vs 10%), and westerly winds were less likely to exhibit a reverse rain shadow than easterly winds (2.3% vs 9.1%).
The findings of this analysis are incorporated into a documentary entitled Chasing Sheffield's Rain Shadow, which is available on YouTube (www.youtube.com/watch?v=3eaVn7JQpOQ).
TOWARD A DEEPER UNDERSTANDING OF THE RAIN SHADOW. This research explores how to quantify the impact that the rain shadow has on individual precipitation events across the United Kingdom.
Galewsky, J., 2009: Rain shadow development during the growth of mountain ranges: An atmospheric dynamics perspective.
Because the definition of a rain shadow does not specify a time scale, using rain gauge data requires selecting a time scale.
Does talking about the rain shadow hour by hour make any sense?
We hope that discussing these issues out in the open will be beneficial to the overall discussion of how to identify and quantify a rain shadow.