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What is climate change?
Climate can be defined as the collective state of the atmosphere for a given place over a specified interval of time. There are three parts to this definition: location, because climate can be defined for a globe, a continent, a region or a city; time, because climate must be defined over a specified period; and the collective state of the atmosphere, which includes averages and extremes of variables such as temperature, precipitation, pressure and winds.
Climate change is a long-term change in the average weather patterns that have come to define Earth’s local, regional and global climates. Continue reading
What is the National Weather Service?
The National Weather Service, or NWS, is an office of the National Oceanic and Atmospheric Administration, NOAA, which sits in the U.S. Department of Commerce. The connection to the Department of Commerce is sensible – it’s estimated that one-third of the U.S. economy is sensitive to weather and climate.
The mission of the National Weather Service is to “provide weather, water, and climate data, forecasts, warnings and impact-based decision support services for the protection of life and property and enhancement of the national economy.” Continue reading
How unusual was our dry and warm October weather?
Meteorologists often compare current temperature and precipitation measurements to “normal” values to interpret unusual weather. The weather data observed over the 30-year period between 1991 and 2020 are used to define “normal” or “average” weather. These normals are recalculated every 10 years. The normals are determined on annual, seasonal, monthly, daily and even hourly timescales. The maximum and minimum values also are tracked for each day of the year.
The weather that southern Wisconsin has experienced this October has been different from our normal October weather. Throughout most of October, we experienced very dry conditions. Prior to the storms that occurred on Oct. 30 and 31, the total precipitation across most of the state was less than 50% of the normal precipitation. This lack of precipitation throughout the month was alleviated during the final two days. Many areas in Dane County received over 3 inches of rain on Oct. 30 and 31. Continue reading
What is a meteorological bomb?
Storm systems that form in middle or high latitudes, in regions of large temperature contrast are called extratropical cyclones. This contrasts with tropical cyclones, such as hurricanes, which form in regions or relatively uniform temperatures.
Extratropical cyclones are surface low-pressure systems where the air at the surface flows counterclockwise in the northern hemisphere and clockwise in the southern hemisphere. The winds around these centers of low-pressure spiral inward at the surface, forcing rising motions. The rising air can result in clouds and precipitation. The process of extratropical cyclone development and intensification is referred to as cyclogenesis. In North America there are favorable regions for cyclogenesis, including the eastern slopes of mountain ranges, the Atlantic Ocean off the Carolina Coast, and the Gulf of Mexico. The jet stream also influences cyclogenesis. Continue reading
Science-based policy is shrinking ozone hole
The Southern Hemispheric ozone hole usually begins to develop in mid- to late August, as the hemisphere emerges from its winter, and peaks in mid-October.
This year it first appeared closer to the end of August and by mid-September was 18.48 million square kilometers in size, smaller than in recent years, including both 2022 and 2023. Though this year’s slow start does not necessarily reflect a recovery of the ozone layer, it does support the notion that expert guidance has made a positive contribution to this vexing problem. Continue reading
