High Winds in High Places

Mount Washington hit by strongest August wind gust on record – New Hampshire, U.S.

Mount Washington hit by strongest August wind gust on record - New Hampshire, U.S.

The Mount Washington Observatory in New Hampshire recorded a wind gust of 237 km/h (147 mph) at the summit on Tuesday evening, August 4, 2020, as post-tropical cyclone Isaias swept through the New England region. This is the strongest wind gust ever recorded at the mountain in the month of August, breaking the previous one set in 1954.

Mount Washington is the highest peak in the Northeastern United States at 1 916 m (6 288 feet). On average, the mountain sees gusts of about 39 km/h (24 mph) during the month of August.

Strong winds from Isaias knocked power to more than 140 000 customers in New Hampshire on Tuesday. Many wires and trees were downed, blocking scores of roads. During the height of the storm, the observatory registered 237 km/h (147 mph), which officially became the strongest gust for the month of August.

The previous record for the strongest wind gust for the month of August was during Hurricane “Carol” in 1954 at 228 km/h (142 mph).

The highest all-time wind gust on Mount Washington was 372 km/h (231 mph) set in April 1934. This was the highest wind speed ever recorded on Earth until 1996 when Tropical Cyclone “Olivia” set a new record at 407 km/h (253 mph) in Barrow Island, Australia.

Featured image credit: Google

from:    https://watchers.news/2020/08/06/mount-washington-hit-by-strongest-august-wind-gust-on-record-new-hampshire-u-s/

Wind Speed, Eclipses, and Temperatures

Eclipses’ effect on wind revealed

March 29, 2012 by Tom Marshall

Eclipses' effect on wind revealedSolar eclipses don’t just turn the lights out; they also make the wind slow down and change direction.

Scientists compared hourly measurements of wind speed and direction from 121  across southern England during the August 1999  with the output of a high-resolution weather  that wasn’t programmed to represent the eclipse.

The model agreed very closely with the instruments’ readings right up until the eclipse began. It then showed what the weather would have been like if the eclipse hadn’t happened, giving researchers a much more accurate idea of its effects.

‘The eclipse was like a giant ,’ says Dr Suzanne Gray of the University of Reading, lead author of the paper in  A. The study shows that scientists can now use high-resolution weather models to look at  changes of small magnitude, like those caused by solar eclipses.

The results show that average  across an inland cloud-free region over southern England dropped by 0.7 metres per second, and that the wind’s direction turned anticlockwise by an average of 17° – effectively, the eclipse was causing the winds to become more easterly. Temperatures also fell by an average of about 1°C.

Previous work on the subject has been based only on measurements in a few places, rather than from a network as in this case. And it didn’t compare these measurements with a weather model to predict what would have happened without the eclipse.

It’s only recently become possible to do this kind of experiment, after huge improvement in high-resolution  models over the last decade. ‘We could never have done this when the eclipse occurred,’ says Gray, ‘but now we can use the model to get a far better idea of its impact on the wind.’

Temperatures are likely to fall when the Earth is deprived of sunlight, just like they do at night. And the slower wind speeds weren’t unexpected, Gray says – cooling the atmosphere close to the ground removes energy from it, damping turbulence, which will probably mean less wind. But the changes in wind direction were more of a surprise.

The effects were so pronounced that they can be seen even in measurements that are taken hourly, which is very infrequent in the context of such a transient event as an eclipse.

The results seem to fit the ‘eclipse cyclone’ hypothesis proposed in 1901 by H Helm Clayton, one of the first scientists to investigate eclipses’ impact on the weather. He suggested that when the moon’s gigantic shadow falls on the Earth, it causes a core of cold air around which a weak, short-lived cyclone forms, skewing the winds anticlockwise.

from:    http://www.physorg.com/news/2012-03-eclipses-effect-revealed.html