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Did weather forecasting play a role in D-Day?
Last Friday was the 81st anniversary of the Allied invasion of Europe that began with the landings on the beaches at Normandy. The combined land, air, and sea assault of June 6, 1944 remains the largest such event in history. The success of the invasion was extraordinarily dependent of weather conditions. More than three months before the invasion, a combined British and American forecasting team began rigorous forecast exercises designed to iron out the physical and logistical kinks of such a coordinated effort. As June drew near, the nature of this collaboration was still problematic as the two groups employed vastly different methods in fashioning the requisite 3-5 days forecasts – at the time, absolutely primitive in the underlying science as compared to what is possible at such ranges today. The British were attempting to make such forecasts based upon the understanding of atmospheric dynamics that had grown substantially during the war. The Americans were employing a method based on a statistically- based search through old weather data for historical analogues that could be used to guide the forecast. Continue reading
Category: History, Meteorology, Severe Weather
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Is there scientific consensus on global warming?
Global warming refers to the recent rise in Earth’s average temperature caused by human activities that emit higher levels of greenhouse gases like carbon dioxide and methane. Scientists understand the physics and chemistry of how these gases warm the atmosphere.
The global average temperature has increased about 1.7°F since 1970. During this same period, temperatures have risen around 2.5°F in the contiguous United States and 4.2°F in Alaska. The 10-year period 2014–2023 was the warmest decade on record. Such warming has, of course, altered average weather conditions, including temperature, precipitation, humidity, wind patterns, atmospheric pressure, and ocean temperatures and so global warming is nearly synonymous with climate change. Although it is difficult to directly attribute specific weather events to global warming/climate change, data analysis indicates that global warming is linked to more extreme weather events such as droughts and floods. There has also been an increase in days with temperatures above 90°F and heat waves. Heat waves, defined as periods of unusually hot weather lasting two or more days, have become more frequent in major cities across the United States, rising from an average of two heat waves per year in the 1960s to over six per year in the 2020s. Continue reading
What is the status of the ozone hole?
This year is the 40th anniversary of the discovery of ozone hole. On 16 May 1985, British Antarctic Survey scientists published research that revealed a significant drop in ozone levels above Antarctica, referred to as the “ozone hole.” Stratospheric ozone loss has also been observed over the Arctic.
Ozone (O3) is a molecule formed by three oxygen atoms. In the lower troposphere O3 is considered a pollutant, as it can cause respiratory problems when breathed. Ozone in the stratosphere absorbs UV rays from the sun, protecting life on Earth from harmful radiation that can cause skin cancer and other health problems.
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Is there a windiest time of year in Madison?
With the pollen season peaking in southern Wisconsin one may wonder if there actually is a windiest time of year in Madison. Of course, a windy day can come along just about any time of year (the record gust of 83 mph in Madison occurred in June 1975) but the climatology suggests that March and April are the windiest months of the year with average wind speeds of 11.3 and 11.4 mph, respectively. November through February are not far behind logging a four-month average of 10.5 mph.
The fact that it’s windier during the cold season is not surprising as that time of year is characterized by the highest frequency of mid-latitude cyclone activity. Mid-latitude cyclones are large in scale, covering several states simultaneously, and are often associated with very large differences in sea-level pressure over small distances. It is these pressure differences that drive the wind. Continue reading
Category: Climate, Seasons, Severe Weather
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Why is May 6 such a special day in weather science history?
Immediately after WW II, it became fashionable to imagine technologies that might allow human beings to control the weather. In fact, one goal advanced by influential scientists was actually to explode nuclear bombs in the right locations and in the right quantity so as to alter the weather in favorable ways. Such an enterprise would require accurate forecasts of the weather thought possible by using the brand new computer technology to make the millions of requisite calculations.
The drive to use computer models for weather forecasting was initiated at a secret meeting at the U.S. Weather Bureau headquarters in Washington D.C. on the rainy morning of January 6, 1946. After a series of successes and setbacks that mostly discouraged the broad meteorological community, the first operational computer generated forecasts were issued on the afternoon of May 6, 1955. Continue reading