The fluid dynamics associated with atmospheric disturbances cause the downstream air (ahead of the disturbance, before it arrives at a location) to rise, and the upstream air (behind the disturbance, i.e., after the disturbance has passed) to sink. If there is sufficient moisture in the area of rising air, clouds and precipitation may form. Necessary … Read more
Imagine yourself as a cloud, happily floating over the surface of the Earth without a care in the world. As you drift across the sky, the millions of tiny water droplets and ice crystals that you are composed of brush against each other, causing a buildup of electric charges in your cloud body. The negative … Read more
Atlanta’s biggest snowfall events of all time are listed in the table below. The most snow ever recorded on a single day in Atlanta was on January 23, 1940 when 8.3 inches fell. The top 10 snowstorms in Atlanta have a median accumulation of 4.2 inches. View the full list We often hear the cliche: … Read more
I love this animation. After spending years trying to explain these concepts, along comes high-resolution satellite images sewn together from a Lagrangian perspective to create a fast animation that actually shows the seasons changing as Earth tilts on its axis from equinox to solistice to equinox and so on. Credit: Simon Proud, researcher in the … Read more
The autumnal equinox occurs Sunday, September 22, 2024 at 7:43 AM, but the days and nights are not considered equal until Saturday, September 26th. This is because of the atmospheric refraction of sunlight. When a wave encounters a medium whose density differs from that through which the wave has been propagating, conservation of momentum and energy … Read more
A follower asked, “if the water cycle is real, how can there be water shortages?” In light of the recent drought in Texas, which ultimately ended with the historic rainfall during the month of May 2015, and the ongoing devastating drought in California, I thought I would make this brief post. What is the Water … Read more
The United States is also home to the most frequent occurrence and the largest variety of extreme weather events of any other country in the world. These events include, but are not limited to, extreme heat/cold, snowstorms, tropical storms and hurricanes, droughts, areal and flash floods, hail storms, and tornadoes. While none of this is … Read more
Cold-air damming (CAD), often called “the wedge” in the Southeast, is an interesting meteorological feature that can result in tricky forecasts for meteorologists. Topography plays a major role in CAD events, and you need a mountainous range for this feature to develop. While CAD can occur in the Rockies, it is predominant east of the … Read more
In atmospheric dynamics, a negatively tilted upper-level trough tends to be stronger and much more dynamic, particularly if there is a closed upper low Both rising air and heavy precipitation (especially snow) work to cool the atmosphere from the top down. This is called dynamic cooling and it is extremely efficient at turning an otherwise … Read more
Before I begin this piece, I want to present a challenge. The following chart shows the actual high and low temperatures for a full month in Atlanta, Georgia. *A condensed version of this writeup was also featured in the Douglas County Sentinel. Challenge: Can you spot the day with a historic snowstorm? During this particular … Read more
The Weather Bureau, now known as the National Weather Service, was established on February 9, 1870 by the 41st United States Congress and signed by President Ulysses S. Grant. On March 29, 1870, the new weather forecasting service was officially assigned to the U.S. Army Signal Service within the Department of War and given the … Read more
If you watched the GA Tech/FSU ACC Championship Game in Charlotte, North Carolina tonight (12/6/14), you may have seen the smoke-filled stadium following the pre-game fireworks show. A heavy fog was already in place, which virtually guaranteed poor visibility of the fireworks; but to make matters worse, the smoke from the fireworks had no where … Read more
In an earlier article, we discussed the dynamics and thermodynamics of lake effect snow. In this post, we discuss the meteorological differences between single-band and multiple-band lake-effect snow events. Keep in mind that all lake-effect snow events are fueled by moisture and latent heat flux from the relatively warm lake water; these fluxes are already … Read more
One of the most awe-inspiring forces of nature is lake-effect snow. The amount of latent energy required to produce the lake-effect convection is astounding, and in some situations, snowfall rates can reach as high as 5 to 6 inches per hour. In this article, we discuss the atmospheric physics, dynamics, and thermodynamics responsible for the … Read more