Archives
Categories
WeatherGuys Links
Category Archives: Phenomena
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
Do all hurricanes have an eye?
Seen from space, a hurricane appears as a vast spiral of clouds stretching across hundreds of miles. Near the center of strong hurricanes is the eye, a roughly circular region of comparatively calm weather, light winds, and low pressure.
The eye is one of the storm’s most recognizable features, but it is not the most dangerous part. That distinction belongs to the eyewall, the ring of towering thunderstorms that surrounds the eye and contains the hurricane’s strongest winds and most intense weather. 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
What is a “wake low”?
Wake lows are short-lived mesoscale phenomena. Mesoscale weather ranges from about 5 kilometers to 1,000 kilometers in size.
Wake lows are relatively uncommon. They produce strong winds after a storm moves out. The term “wake low” was defined by Ted Fujita, the same meteorologist who came up with the F-scale ranking of tornadoes. These areas of low-pressure form on the backside of heavy rain, causing winds to surge in at fast speeds. Continue reading
What is fire weather?
Wildfires need three essential elements: heat, oxygen and dry fuel. Fire weather refers to a mix of meteorological conditions that make it easy for wildfires to ignite and spread quickly. The main weather factors are low humidity, strong winds, warm temperatures and atmospheric instability.
When humidity is low, moisture is drawn out of plants, turning them into highly combustible fuel for fires. Extended dry spells or droughts remove the moisture that helps prevent ignition, making the physical environment more vulnerable. Strong winds provide fires with oxygen and carry hot embers ahead of the fire line, starting new fires. Warm temperatures heat dry vegetation, making it more likely to ignite. Unstable atmospheric conditions allow smoke plumes to rise rapidly, intensify fires, and create unpredictable shifting winds. Continue reading
