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Greenburgh Public Library Blog


by Christa O'Sullivan on 2019-11-05T14:00:00-05:00 in Science | Comments

Weather affects us all, whether we like it or not. I’m a librarian here at Greenburgh but as many of my fellow staff members will tell you, I tend to act as the in house meteorologist. Growing up and living in the northeast, the seasons always fascinated me. Factoring in that I am a librarian, I decided to do some research about why weather happens when it does. 
When you watch the weather, you may feel like meteorologists are talking in a code that you just don’t understand. Bomb Cyclone, Thundersnow, Sun Dog, this is just the start of some terms you may here on your morning news. How did these names come about? Read on to find out more.
This may sound like a strategy for a Super Mario Nintendo game but a bombogenesis is a very real (and severe) weather happening that can occur no matter what season you are. A bombogenesis is defined as a storm that undergoes rapid strengthening. It is usually referred to as a bomb cyclone or a bombogenesis if it drops more than 24 millibars over 24 hours. A millibar is what measures atmospheric pressure. Usually this happens when two different air masses collide, often a cold and warm air mass. The main effects of a storm “bombing out” are increased winds and precipitation, which can be in the form of snow or rain. 
Thundersnow is just that, a storm in the winter. One might think that thunderstorms only occur in the summer when we get the hot humid weather but they can actually occur in the winter too. This can happen when the air becomes unstable enough to support a storm. When enough moisture rises above the surface a storm can occur. As I talked about in my last post, the ingredients are the same for a winter storm and a summer storm, moisture (usually from the ocean), instability (when warm air rises) and a lifting mechanism (air density). One last thing about thundersnow, you’ll likely have more to shovel! 
Sun Dogs:
A sun dog might seem like a yoga pose but it’s actually a very beautiful sight. According to, “sundogs are colored spots of light that develop due to the refraction of light through ice crystals.”  You can tell it's a sun dog because of the colored patches of light near the sun. The scientific name for a sun dog is, “parhelion (plural: parhelia) from the Greek par─ôlion, meaning "beside the sun.” Fun fact, you will most likely see these on very cold days when there are more ice crystals to refract the light. 
A derecho is a severe thunderstorm with a very specific type of wind. Many times derechos are confused with tornadoes. The difference is that their winds are in one direction and follow a straight path. This is why derechos are sometimes referred to as straight line winds. A straight line wind is classified as a derecho when the destruction is more than 240 miles and includes gusts of more than 58 miles per hour

If you’re interested in learning more about interesting weather terms, try out these resources available at the library:

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