Last Monday the solar eclipse plunged parts of North America into around two minutes of darkness for the first time in 38 years. However, solar eclipses modify more than just the sunlight, with a domino effect on the weather too.
Unsurprisingly, whilst clear skies are favoured for viewing conditions, they also produce marked weather changes in both temperature and surface winds. Beneath cloudy skies, the temperature decrease will be minimised as less heat is lost from the Earth’s surface. But the average temperature drop under clear skies in the path of totality is between 5F and 10F. An 11F drop was recorded in Pocatello, Idaho.
Similarly, warm air stops rising in the absence of solar radiation, and this results in a reduction of wind speed and shift of direction. Winds on average fall by around 2mph during totality, with Wilmington, Ohio observing up to a 5mph drop in wind speed.
Elsewhere, heavy rain inundated Sierra Leone last week, inducing a devastating mudslide which swept away thousands of homes, killing nearly 500 people. Sierra Leone’s rainy season runs from May to October, with July and August being most notably wet and humid; since 1 July however, the region has seen over 100cm of rain – three times its average.
Typhoon Hato, the strongest storm since 1968, lashed southern China last week in a destructive path across Hong Kong and Macau, triggering large ocean swells that submerged the streets. Wind gusts reached over 100mph, flattening buildings and killing 16 people, with many others still missing.
