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What causes lightning?
Charges form in a storm composed of ice crystals and liquid water drops. Winds inside the storm cause particles to rub against one another, causing electrons to be stripped off, making the particles either negatively or positively charged.
The charges get grouped in the cloud, often negatively charged near the bottom of the cloud and positively charged up high. This is an electric field, and because air is a good insulator, the electric fields become incredibly strong. Continue reading
What is an atmospheric river?
Atmospheric rivers are relatively narrow regions in the atmosphere — typically 250 to 375 miles wide and well over 1,000 miles long.
These sky rivers transport water vapor outside of the tropics to mid-latitude and polar regions. We estimate that 90% of Earth’s north to south water vapor transport is done through atmospheric rivers. Continue reading
How do radars see tornadoes?
A weather radar consists of a transmitter and a receiver. The transmitter emits pulses of radio waves outward in a circular pattern. Precipitation scatters these radio waves.
“Reflectivity” is the amount of transmitted power returned to the radar and measured by its receiver. The intensity of this received signal indicates the intensity of the precipitation.
Measuring the time it takes for the radio wave to leave the radar and return tells us how far away the storm is. The direction the radar is pointing locates the storm. Continue reading
How did the Tonga eruption affect the atmosphere?
Hunga Tonga erupted on Jan. 15 and lasted 11 hours.
It devastated the region, covering the land in a layer of ash. The eruption blasted a plume of ash and water vapor 34 miles into the atmosphere — into the mesosphere.
The Hunga Tonga plume contained only a very small amount of sulfur dioxide (SO2). Sulfur dioxide from volcanic mega-eruptions that reach high in the atmosphere can have an impact on global temperature. The mega-eruption of Pinatubo in 1991 released enough sulfur dioxide to cool the Earth’s surface for three years. The Tonga eruption will not have that kind of impact. Continue reading
How common are extreme winds in the Front Range of the Rocky Mountains?
This winter has already delivered some notable disasters, and it is important to carefully consider the anatomy of such high impact weather events in order to, as accurately as possible, understand to what degree an event is attributable to the … Continue reading
Category: Meteorology, Phenomena, Weather Dangers
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