The Science of Weather

We experience weather everyday, but do we really know what it means? In its basic sense, weather is the state of the atmosphere at any given time with respect to wind, temperature, cloudiness, moisture and pressure. Floods, thunderstorms and hurricanes are a few extreme manifestations of weather. Do you know any more? Click here to learn about other weather related terms.

Weather plays an important role in our daily lives. One of the first things many of us do in the morning is check the weather. Some may search the newspaper or television for the day’s forecast, while others may make observations by peaking out doors or windows. Why do we do this? Well, weather determines what we wear, what we do and where we go. More importantly, knowing what to do in the case of extreme weather can save our lives. That’s why meteorology is so important. By definition, meteorology is a type of science that deals with atmosphere and its phenomena, especially with weather and its forecasting. Generally, the person you see on the news delivering the weather forecast is a meteorologist. There are many other career options in the field of meteorology, such as a climatologist or a radar meteorologist. In addition, a career in meteorology could lead to job opportunities at NASA, the National Weather Service or the military.

Now that we know a little more about weather, lets talk about some of its extremes. From blizzards and hurricanes to droughts and tornados, the world of weather is dynamic. In the months to come we’ll tackle each of these weather extremes. Lets kick off with blizzards.

Blizzards

The majority of us have seen snow at some point in time. You know the white stuff that falls from the sky when it’s cold outside. Whether you’ve felt its icy touch or seen it on TV, you have a general idea of what snow is. What about blizzards? They involve snow, but depending on where you live you may not have experienced one. So lets find out more about these winter storms.

Standing tall on North Dakota snow A March blizzard nearly buried utility poles. Caption jokingly read "I believe there is a train under here somewhere!" 
 (1966)

Credit: Collection of Dr. Herbert Kroehl, NGDC

Blizzards are severe winter storms that bring high winds and blowing snow, which makes for low visibility. According to the National Weather Service, a blizzard is a storm with winds 35 miles per hour (mph) or greater and heavy snowfall and/or blowing snow that reduces visibility for less than ¼ mile for three hours are longer. A severe blizzard has temperatures nearing 10°F or below with winds greater than 45 mph and snowfall that reduces visibility to near zero. Heavy snowfall and low temperatures usually accompany blizzards, but are not necessary for them to occur. Ground blizzards can form when strong winds pick up snow that has already fallen.

Red Cross workers search for victims buried in cars following snowfall during the Blizzard of "77." Only about 12 inches of new snow fell during this event but high winds coupled with existing snow in western New York and accumulated snow on the surface of frozen Lake Erie combined to cause major difficulties. 
 (Feb 1977)

Credit: American Red Cross

How do they form?

You need three things for a blizzard to form: cold air, moisture, and lift. See below for the blizzard recipe.

1. Cold air (below freezing) for snow: It’s a funny thing; snow won’t fall to the ground unless it’s cold. It needs to be cold both up in the clouds for snowflakes to form and down at ground level for snow to stick.
2. Moisture to form clouds and precipitation: Moisture in the air is called water vapor. Generally blizzards form near some body of water. That’s why air that blowing across a large lake or ocean is an excellent source of water vapor. As wind moves air over the water, some water evaporates from the surface, leaving vapor in the air.
3. Warm, rising air is needed to form clouds and cause precipitation: The formation of a blizzard is due to warm air rising over cold air. So, how can this happen? In one of two ways. Winds can pull cold water toward the equator from the poles and bring warm air toward the poles from the equator. When warm air and cold air are brought together, a front is formed and precipitation occurs. Warm air can also rise to form clouds and blizzard snows as it flows up a mountainside.

Where do most blizzards occur?

Blizzards occur at a higher frequency in the upper Midwest and Great Plains of the United States. However, blizzards can occur in any location that has a climate that experiences snowfall.

The Great Blizzard of March 12, 1888. 


Credit: National Oceanic and Atmospheric Administration/Department of Commerce

What to look out for during a blizzard?

• Hazardous driving conditions
• Very low wind chills. Exposure to low wind chills could lead to frostbite or hypothermia.
• Power outages
• Frozen pipes
• Low fuel supply

Sources:

National Weather Service-Flagstaff

weather.com

Web Weather for Kids

weatherwizkids.com