photo: Dennis Jernberg/Creative Commons
Let's take as given that there have always been weather extremes, both hot and cold, throughout history and there is indeed a component of natural variability at play. But that's far from the whole story. If you're wondering what makes the latest heatwave different from those that have occurred before, Weather.com has a pretty good summary (h/t Climate Progress). In short, the nature and context of this summer's situation is what sets it apart.Weather.com senior meteorologist Stu Ostro writes,
This time, the extreme drought, heat, and wildfires are occurring along with US extremes this year in rainfall, snowfalls, flooding, and tornadoes, and many other stunning temperature and precipitation extremes elsewhere in the world in recent years as well as, as I posted on my TWC Facebook "fan" page, record-shattering 500 millibar heights in lattitudes. And all of this is happening while there's an alarming drop in the amount of Arctic sea ice.
In more concrete examples, Ostro explains how alongside areas receiving record amounts of rain, the dry soil conditions are contributing to record high temperatures and how these are contributing to how hot it feels.
Rather than some of the sun's enery going into evaporating soil moisture, it gets efficiently converted into quickly-rising temperatures each day. And in turn, the soil dries out even more, worsening the drought. ...
Soil and crop moisture evaporating will boost the dewpoint, which translates to how humid the air feels.
Read more, it's pretty fascinating stuff, especially considering these sort of conditions are likely to become more usual in coming years and decades: The ridge, heat, humidity, drough, and Dust Bowl
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