Ivor, Borth and Ynyslas’ Katabatic Wind
Along with the rest of the country we have been enjoying some gorgeous spring weather recently. Clear blue skies all day long and some of the most amazing sunsets and sunrises with spectacular oranges, pinks and purples. It has been quite cold too, especially at night which leads to a local phenomenon of a katabatic wind, affectionately known as Ivor here in Ynyslas and Borth.
It works in a similar fashion to a sea-breeze in the summer, but in the opposite direction and with more force. At night the temperatures in the hills can drop significantly, often reaching minus numbers and maybe even down to minus 8-10ºC. The sea however remains at a fairly constant temperature and is currently around 9ºC. That is a huge temperature difference. The sea warms the air above it which then rises, and cooler air from inland moves in to take its place, creating an offshore wind. As the sun rises in the mornings, it rays reflect off the surface of the sea further raising the temperature of the air above it which drives the wind even faster. This is the exact opposite to the summer sea-breeze effect, but the larger temperature difference increases the effect making the winds stronger.
On top of this, Ivor, the katabatic wind has gravity on its side (unlike the sea-breezes in the summer). The cold air in the hills sinks into the valleys and flows along them just like a river would. Gravity, coupled with topographic funneling in association with winds driven by a temperature gradient can produce some pretty startling effects here, with winds in excess of 20 knots when everywhere else is calm. If this also occurs on a day when there is a general E-NE wind direction then we often gets winds in the 30-40 knot range. More than enough for most people and perfect for those of us who windsurf and Kitesurf.