Weather is a complex dance of atmospheric forces, sometimes creating strange and fascinating phenomena while signaling danger through the shapes of clouds.
Tsunami Clouds – A Rare Cloud Type Appearing Before Storms
Tsunami Clouds. (Photo: Climavision)
First, we must mention tsunami clouds – another name for shelf clouds, a unique natural phenomenon that looks terrifyingly similar to rolling ocean waves and often appears before thunderstorms and hurricanes.
This is a distant cloud band associated with storms, also known as “shelf clouds” or tsunami clouds, which are one of two types of arcus clouds, with the other type being roll clouds. These clouds typically form along the leading edge of a storm. They are a sign of a strong storm. The cloud band will cause heavy rain and lightning in the areas where it appears.
Shelf clouds develop when cold, dense air is pushed into warmer air by the wind. Such abrupt movements often occur in strong downdrafts associated with thunderstorms. The cold air rushes down to the ground before spreading out in all directions. When the shelf clouds sweep through, wind directions change suddenly, and wind speeds increase, leading to heavy rain or hail within minutes.
Virga: Ghostly Rain
Virga indicating an important process occurring in the atmosphere. (Photo: Climavision).
Virga presents a surreal sight in the sky – a phenomenon where rain or snow never touches the ground. This captivating occurrence happens when moisture falls from clouds in the form of rain or ice but evaporates before reaching the ground. The reason for this phenomenon is the atmospheric conditions where the air beneath the clouds is extremely dry, absorbing all the moisture before it can make contact with the ground.
When rain or snow falls from the base of the cloud, it encounters dry air that causes it to evaporate quickly. What remains are thin streaks, resembling the initial trail of precipitation before it turns into water vapor. These streaks, sometimes appearing like fine hair, show a complex interplay between moisture and high-altitude air currents.
Although virga may seem like merely a visual effect, it signifies an important process occurring in the atmosphere. Sometimes, a strong, brief gust of wind can disperse the cloud. Despite large storms forming high above, the only evidence on the ground may be the virga streaks hanging in the sky, leaving an air of mystery and fascination.
Fujiwhara Effect – Storms Interacting
Typhoon Parma (left) and Typhoon Melor (right) interacting in the Philippine Sea on October 6, 2009. (Photo: NASA)
The Fujiwhara Effect reveals the interaction when two cyclonic storms draw near each other. As the storms come closer together, their proximity and similar rotational movements initiate a complex interaction. Depending on their relative strengths, various outcomes can occur. If one storm is significantly stronger than the other, the smaller storm may rotate around the larger one, eventually merging or being absorbed. Conversely, storms of comparable strength may attract each other, rotating around a common center before separating or merging into a more powerful storm.
The outcome of the Fujiwhara Effect often leads to the merging of these storms into a colossal storm. The most recent occurrence was in 2017 when storms Hilary and Irwin interacted in the eastern Pacific off the coast of Mexico.
Tornadoes
Tornado. (Photo: Justin/Wikipedia).
A tornado is a phenomenon characterized by a rotating column of air extending from a thunderstorm to the ground.
Tornadoes usually develop from thunderstorms, often from very strong or supercell thunderstorms, so wherever there is severe thunderstorm activity, there is a potential for tornadoes. They can also originate from strong gust fronts (called downbursts) or from a hurricane. It is believed that when cold air aloft presses down on warm air below, the warm air is forced to move upward very strongly. However, when tornadoes occur over water, convection is often not visible, and there may not be a temperature difference between the layers.
Tornadoes can take on the shape of a funnel, cone, or spiral. When this funnel-shaped tornado sweeps through, it can pick up anything in its path.
