Category Archives: Meteorology

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

Category: Meteorology, Phenomena

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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

Category: Meteorology, Severe Weather

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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

Category: Meteorology, Phenomena

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Is wildfire season getting longer?

Wildfires are an important part of many ecosystems and an essential part of forest and rangeland health.

Fires require fuel to burn, heat to ignite and oxygen to burn. Wildfire season is defined as the time of year when wildfires are most likely to ignite and spread. A combination of high temperatures, low humidity, lack of precipitation days and high winds make wildfires more likely to spread and lengthen fire seasons. Continue reading

Category: Climate, Meteorology, Severe Weather

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What is the wet-bulb temperature?

The wet-bulb temperature is the lowest temperature to which unsaturated air can be cooled by evaporating liquid water into it.

This may sound horribly obscure, but it serves as a very useful measure of human comfort. It combines atmospheric humidity and temperature in a way that helps determine our comfort level while in the shade, especially during hot and humid conditions. Continue reading

Category: Meteorology, Seasons

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