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Category Archives: Phenomena
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
Is global warming impacting bird migration?
Global warming refers to the rise in global temperatures due to the increasing concentrations of greenhouse gases in the atmosphere. One impact is that northern latitudes are experiencing warmer mean annual temperatures and experiencing earlier springs, milder winters and delayed falls.
Bird migration is a natural phenomenon that involves the seasonal movement of birds from one place to another. Their evolutionary adaptation allows species to take advantage of seasonal resources and avoid harsh winter conditions. Because seasonal change is a dependable feature of our planet, migratory bird species have adapted to this seasonality as it coincides with the optimal conditions for feeding, breeding and raising their young. Continue reading
What is the tornado scale?
A tornado is a powerful column of winds that rotate around a center of low pressure. The winds inside a tornado spiral inward and upward, often exceeding speeds of 300 mph. We classify the strength of a tornado after trained observers assess the damage it did to the area.
All tornadoes are assigned a single number from the Enhanced Fujita Scale (EF) according to the most intense damage caused by the storm. When tornado-related damage is surveyed, it is compared to a list of damage indicators and degrees of damage to help estimate the range of wind speeds the tornado likely produced. The rating is assigned based on a set of 28 damage indicators, such as barns, schools and trees; the degree of damage to each one is used to determine the EF scale of every tornado. Continue reading
