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How do we know if an extreme weather event is due to our changing climate?
Weather events result from an interaction of many factors, including current conditions of the atmosphere. Weather is considered extreme when it’s far outside of normal for a particular place and time. Weather-related extreme events include heat waves, freezes, heavy downpours and tornadoes. Attributing an extreme weather event to the observed climate change is referred to as the science of extreme event attribution.
Researchers take two complementary approaches to explore the cause-and-effect relationship between climate change and extreme weather. One method analyzes the statistics of how often a type of extreme event occurs in our current climate with how often the event occurred in a climate without human-caused climate change. This approach relies on improved climate model simulations. The other approach examines how climate change has altered the characteristics of the event. As an example, heat waves have become hotter because the atmosphere has warmed. Continue reading
Category: Climate, Meteorology, Severe Weather
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What is considered “heavy rain”?
The National Weather Service defines rainfall rate as the intensity of liquid precipitation falling over a specific, short duration, typically expressed in inches or millimeters of accumulation per hour.
The American Meteorological Society defines heavy rain as a rainfall rate of 0.30 inches of rain per hour. Rainfall rate measures how hard rain falls at any given moment, while accumulation measures the total depth of water accumulated. Continue reading
Two Questions about Clouds
Clouds are composed of tiny liquid water droplets, whose diameters are about the width of a human hair, and tiny shards of ice in a variety of shapes, or habits. Whether a cloud is mostly liquid water droplets or ice particles depends, as you might guess, on the ambient temperature of the air in the cloud.
Tiny cloud liquid water droplets can remain in the liquid state to temperatures as low as about 14 degrees Fahrenheit, and when they do they are known as supercooled liquid water droplets. These droplets feel the downward directed force of gravity just like a baseball or a watermelon would. Because the droplets are so small, and therefore have small masses, the gravitational force can easily be balanced by an upward directed friction force resulting from the interaction of the droplets with the air molecules around them and so the droplets remain suspended. Continue reading
Why is wildfire smoke unhealthy?
The smoke from wildfires can linger in the air and often travels long distances carrying unhealthy matter.
Depending on how hot the fire is and what’s burning — trees, grasslands, or buildings — wildfire smoke can contain toxic chemical substances, including carbon monoxide, carbon dioxide, sulfur dioxide, nitrogen oxides, benzene and metals. The smoke can also change over time and become more toxic. Continue reading
What is atmospheric ducting?
Atmospheric ducting is a phenomenon that affects how radio waves travel through our atmosphere.
Radio waves are a type of electromagnetic energy that carry information as they travel by modifying certain properties of the wave, like their amplitude or frequency. In a vacuum, radio waves travel at the speed of light. In Earth’s atmosphere, radio waves travel at very nearly the speed of light. Continue reading
