• degree-day—1. Generally, a measure of the departure of the mean daily temperature from a given standard: one degree-day for each degree (°C or °F) of departure above (or below) the standard during one day.

Degree-days are accumulated over a “season” at any point during which the total can be used as an index of past temperature effect upon some quantity, such as plant growth, fuel consumption, power output, etc. This concept was first used in connection with plant growth, which showed a relationship to cumulative temperature above a standard of 5°C (41°F). Recently, degree-days have been more frequently applied to fuel and power consumption, for example, heating degree- day, cooling degree-day. In the life sciences, the standard is often referred to as the base temperature or upper threshold, depending on whether the standard is used as a lower or upper limit, respectively. As used by the U.S. Army Corps of Engineers, Fahrenheit degree-days are computed as departures above and below 32°F, positive if above and negative if below. To avoid confusion, it might be well to call this a “freezing degree-day.” The advantages and disadvantages of the latter concept are discussed well by Sakari Tuhkanen (1980). Compare degree-hour. 2. Common contraction for heating degree-day.
Tuhkanen, S., 1980: Climatic parameters and indices in plant geography. Acta phytogeographica Suecica, 67, Svenska Vaxgeografiska Sallekapet, Uppsala, 105 pp.

The concept of a degree-day can be confusing.  We most often see it used in terms of heating degree-days and cooling degree-days when looking at the daily local climatology reports issued by the National Weather Service.  In that case, a heating degree-day is based on the number of degrees the daily mean temperature goes below 65 degrees Fahrenheit, and a cooling degree-day is based on the number of degrees the daily mean temperature goes above 75 degrees Fahrenheit.  Why are the cooler days called “heating degree-days”?  Because, it is a measure used to estimate the electrical power needed to heat a home back up to a “normal” level.  The opposite is true for “cooling degree-days.” 

For example, on February 12, 2012, in Raleigh, NC, we had a daily mean temperature of 32 degrees (a low of 21 degrees F and a high of 42 degrees F). 

65-32=33 heating degree-days

graupel—Heavily rimed snow particles, often called snow pellets; often indistinguishable from very small soft hail except for the size convention that hail must have a diameter greater than 5 mm.

Sometimes distinguished by shape into conical, hexagonal, and lump (irregular) graupel.

Most non-meteorologists have never heard the term graupel, and would not know it if they witnessed it.  Have you ever seen something fall from the sky and thought “is it snow?” or “is it hail?” ?  It might have been graupel.  Graupel basically starts as snow, but as it falls through the atmosphere, it collects a layer of ice (this act is called “riming”), so that, by the time it hits the surface, it is no longer a snowflake.  Instead it’s in the form of a tiny pellet.  Graupel is different from sleet in that sleet is actually frozen raindrops and tends to be translucent. 

Technical Note: the interview was recorded in stereo with each person’s voice on a separate channel.

As a first try, I am taking my first “What’s Your Weather Job?” interview ever and making it available as an audio file.  Here is WRAL-TV meteorologist Nate Johnson describing his job as a weather producer at a busy TV station and answering questions about what he sees for the future of his chosen career path:

What’s your weather job, Nate Johnson?

If you haven’t had the chance yet, and you’d like to watch our video interviews with meteorologists about their jobs and research, check out our video page!

No warning? Really? The Storm Prediction Center issued a PDS (Particularly Dangerous Situation) Tornado Watch hours before the storms got started. On Sunday morning, meteorologists on facebook, twitter, and other social networking sites (myself included) were warning their friends and followers about the potential for a major outbreak that evening. All you had to do was open your eyes. There were warnings everywhere!

So even with social media, the strong online presence of the Storm Prediction Center, the National Weather Service, private companies like weather.com, the weather underground, etc., NOAA weather radios, text alerts from local TV stations, local Emergency Broadcast/Alert Systems, and more, a national news anchor can still claim that the storms struck without warning? What does she or anyone else making that claim want? A knock on the door? “Hello, I’m your friendly neighborhood weather woman. You may want to pay attention today because we have a severe weather threat in the forecast.” That’s not going to happen.

If a tree falls in the forest and no one is there to hear it, does it make a sound? Of course, it does! The meteorologists were yelling “timber!” on Sunday. Anyone not paying attention can’t claim they didn’t try to warn him or her. All they can do is claim ignorance, and with so many ways available to get warnings now, ignorance is no excuse.

ABC News should issue a formal apology to meteorologists everywhere for insinuating that we weren’t doing our job. The news is not about the anchor’s perspective. It should be about the facts, and the facts are – THERE WAS WARNING. The warnings began days in advance as meteorologists started to see the potential threat develop in the forecast models. When the potential became more concrete, the warnings became more numerous and louder. The day of the event, the warnings were everywhere. The meteorologists were doing their jobs, Ms. Anchor Woman. Why don’t you do yours?

To that end, the AMS is hosting its 2nd Annual Reception for Young Professionals at this year’s AMS Annual Meeting.  Here is the information quoted from yesterday’s email:

What: 2nd Annual Young Professionals Reception sponsored by SAIC Date:
Sunday, January 22, 2012
Time: 9pm – 11pm
Location: Hilton Riverside Hotel, Grand Salon A

There will be a business card competition to encourage networking at
the event, so please remember to bring your business cards. It doesn’t
matter if you printed them at home or they are professionally printed!

Now for the repeating of an old post.  It was one of our first after launching whatever-weather, and I still believe the message is a valuable one. I did make some minor edits just to update the info a bit.

The Art of Networking

January 29, 2010

There’s an old saying that it’s not what you know, but whom you know.  In the business of meteorology, I think it is really about both.  You have to know the weather, but knowing the right people helps in a big way when job hunting.  So how do you get to know the right people?  By networking, of course!

There are a few things to consider when thinking about the art of networking.  First, no matter what a person’s position in life is right now, it will likely change in the future.  In other words, the person you meet today might be a second-year meteorology student struggling to comprehend atmospheric thermodynamics, but a few years from now, that person could be a hiring manager for a major company.  Introduce yourself to the students and professionals alike in this field.  No one knows what the future holds.

If possible, never miss an opportunity to network in person.  Those opportunities come in the form of conferences both big and small.  I have made some great connections at the National American Meteorological Society’s conferences.  With thousands in attendance, it would be difficult not to.  I have made almost as many good connections at the Minnesota Skywarn Workshop.  Wherever you happen to be, in order to really meet people, you have to put yourself out there.  Introduce yourself.  At conferences and workshops especially, you know you have something in common with the other participants.  It should be easy to start a conversation.  Seriously.  Even non-meteorologists start conversations by talking about the weather, right?

If you can’t afford to hit the many conferences and workshops around the country, focus on a more local type of gathering.  A good example is the local chapter of the AMS.  Not only do you meet people with similar interests, but you get to share ideas and information in a more intimate setting.  The knowledge I have gained from those meetings has helped me along my path in this business.

Beyond face-to-face meetings, there is a plethora of ways to network on the Internet including LinkedIn, twitter, and facebook among others.  LinkedIn lets you post your own professional profile, connect with others in the same business, and join groups of like-minded people.

Twitter is a bit more simple and complicated at the same time.  It may take longer to weed through the huge number of users to find those with similar interests, but they are out there.  When you find them, you will suddenly find many more like them by using “features” like #FollowFriday.  The use of twitter could be an entire blog in itself, really.  By the way, you can find us on twitter, too!

How you use Facebook depends entirely on your own preference.  For example, I use it to keep up with people that I truly know and have chatted with face-to-face with a few rare exceptions.  For me Facebook is more personal and I can really be myself on my own page without worrying too much about what my friends think.  After all they are my friends.  For others, Facebook is another way to really expand their professional networks.  Whatever-Weather has a group page and a “fan” page on Facebook.  Please join us there.  You might just meet new people that way, too.

The goal of networking goes beyond just making new acquaintances.  In the process, you have the opportunity to learn new things, too.  For example, you may be a life-long broadcast meteorologist and you meet a NASA space weather scientist.  Think of all of the possible subjects you can discuss and information you can share!  You could tell her about life in front of a green screen and being recognized in the grocery store.  She could tell you how sunspots effect the earth’s global temperatures.  Then you both walk away better on yet another level for having spoken with each other.

In summary, there are multiple ways to network, and I have only covered a few here.  However you choose to do it, networking always starts with one thing: an introduction. “Hi, my name is Nicolle. I co-own Whatever-Weather.com.  What do you do?”

• thunder—The sound emitted by rapidly expanding gases along the channel of a lightning discharge.

Some three-fourths of the electrical energy of a lightning discharge is expended, via ion–molecule collisions, in heating the atmospheric gases in and immediately around the luminous channel. In a few tens of microseconds, the channel rises to a local temperature of the order of 10 000°C, with the result that a violent quasi-cylindrical pressure wave is sent out, followed by a succession of rarefactions and compressions induced by the inherent elasticity of the air. These compressions are heard as thunder. Most of the sonic energy results from the return streamers of each individual lightning stroke, but an initial tearing sound is produced by the stepped leader; and the sharp click or crack heard at very close range, just prior to the main crash of thunder, is caused by the ground streamer ascending to meet the stepped leader of the first stroke. Thunder is seldom heard at points farther than 15 miles from the lightning discharge, with 25 miles an approximate upper limit, and 10 miles a fairly typical value of the range of audibility. At such distances, thunder has the characteristic rumbling sound of very low pitch. The pitch is low when heard at large distances only because of the strong attenuation of the high-frequency components of the original sound. The rumbling results chiefly from the varying arrival times of the sound waves emitted by the portions of the sinuous lightning channel that are located at varying distances from the observer, and secondarily from echoing and from the multiplicity of the strokes of a composite flash. See electrometeor.

 ~Plus~

 snow—Precipitation composed of white or translucent ice crystals, chiefly in complex branch hexagonal form and often agglomerated into snowflakes.

For weather-observing purposes, the intensity of snow is characterized as 1) light when the visibility is 1 km (5/8 statute mile) or more; 2) moderate when the visibility is less than 1 km (5/8 statute mile) but not more than 1/2 km (5/16 statute mile); and 3) heavy when the visibility is less than 1/2 km (5/16 statute mile).

Believe it or not, “thunder snow” is not actually in the glossary despite the excitement the phenomenon brings to weather lovers everywhere.  Well, maybe not everywhere.  Thunder snow is actually quite hard to witness.  For it to occur, a snow storm must have enough convective acceleration (energy transfer) to create lightning and the thunder that follows.  Typically, in the U.S., this occurs with a strong Nor’easter or lake/ocean effect snow storms.  On even rarer occasion, someone farther inland, could witness the phenomenon, but most run-of-the-mill snow storms don’t have enough convection to produce the effect.  Whether you love or hate snow, consider yourself lucky if you’ve ever experienced thunder snow.

virga—(Also called Fallstreifen, fallstreaks, precipitation trails.) Wisps or streaks of water or ice particles falling out of a cloud but evaporating before reaching the earth’s surface as precipitation.

Virga is frequently seen trailing from altocumulus and altostratus clouds, but also is discernible below the bases of high-level cumuliform clouds from which precipitation is falling into a dry subcloud layer. It typically exhibits a hooked form in which the streaks descend nearly vertically just under the precipitation source but appear to be almost horizontal at their lower extremities. Such curvature of virga can be produced simply by effects of strong vertical wind shear, but ordinarily it results from the fact that droplet or crystal evaporation decreases the particle terminal fall velocity near the ends of the streaks. Under some conditions, virga are associated with dry microbursts, which are formed as a product of the evaporation. See cloudclassification.

Virga is another of our favorite weather words.  Basically, it’s liquid or frozen precipitation (rain, ice, or snow) falling from a cloud, but not reaching the ground because the air below the cloud is too dry.  The precipitation evaporates in the drier air.  I love it for two reasons: it has a very cool visual effect, and it can tell you something about the layer of the atmosphere closest to the surface.  By definition, you know the ground layer has drier air, but you might also be able to deduce something about the wind speed and direction between the cloud and the ground based on its appearance.

albedo—The ratio of reflected flux density to incident flux density, referenced to some surface.

Albedos commonly tend to be broadband ratios, usually referring either to the entire spectrum of solar radiation, or just to the visible portion. More precise work requires the use of spectral albedos, referenced to specific wavelengths. Visible albedos of natural surfaces range from low values of ∼0.04 for calm, deep water and overhead sun, to > 0.8 for fresh snow or thick clouds. Many surfaces show an increase in albedo with increasing solar zenith angle. See also plane albedo, planetary albedo, spherical albedo, directional-hemispherical reflectance, bihemispherical reflectance.

To put it in plain English, albedo is a fraction or proportion.  The more reflective a surface is, the higher its albedo.  For instance, fresh snow has an albedo of 80-95% and black top has an albedo of 5-10%.  Bodies of water and darker surfaces absorb more of the sun’s radiation while snowpack and lighter surfaces reflect more of it.  Earth’s average albedo is 31%.  Average, as stated in a previous blog entry, is not a fixed number: it can change.  So what might change the earth’s albedo from day to day?  Adding more dark objects such as roofs and roads or having a greater amount of snow pack over the land surface are obvious examples. 

Why is albedo important and what role might it play in our weather?  Here’s one example: there is something called the urban heat island effect that many meteorologists have to be aware of when forecasting for metropolitan areas.  The higher concentration of low albedo (darker) objects creates a warmer environment.  I saw a prime example of this effect one afternoon in the Twin Cities in Minnesota when the cold front’s dramatic drop in temperatures surrounded the urban area on all sides before it was seen within Minneapolis and Saint Paul themselves, and then, they didn’t get as cold (by just a couple of degrees, mind you) as the outlying areas.

Albedo is different for melting snow pack and darker ground

bright sunshine—Solar radiation intense enough to cast distinct shadows.  See insolation.

insolation—1. (Contracted from incoming solar radiation.) In general, solar radiation received at the earth’s surface.

See terrestrial radiation, direct solar radiation, global radiation, diffuse sky radiation, atmospheric radiation. 2. The amount of direct solar radiation incident upon a unit horizontal surface at a specific level on or above the surface of the earth.  Compare solar constant, total solar irradiance.

solar radiation—The total electromagnetic radiation emitted by the sun.

To a first approximation, the sun radiates as a blackbody at a temperature of about 5700 K; hence, about 99.9% of its energy output falls within the wavelength interval from 0.15 to 4.0 μm, with peak intensity near 0.5 μm. About one-half of the total energy in the solar beam is contained within the visible spectrum from 0.4 to 0.7 μm, and most of the other half lies in the near-infrared, a small additional portion lying in the ultraviolet. See insolation, direct solar radiation, diffuse sky radiation, global radiation, extraterrestrial radiation, solar constant, total solar irradiance.
Fritz, S., 1951: Compendium of Meteorology, 17–19.

We non-scientifically polled our friends on what their favorite weather words were.  Sunshine was in the top three.  Cumulonimbus and thunderstorm were the other two.  Incidentally, you usually can’t have a good thunderstorm without at least a little bit of strong sunshine.

The definition of sunshine is simple enough until you look a little farther into what makes up solar radiation, which is why our weather word is, well, more than one word.  It is more like a drill-down definition, which might get a little too technical for the layman’s needs.  Since the point of this feature is to simplify the term, we won’t go too far into technical details here.  Feel free to use the link above to surf the Glossary for more information.

Sunshine is solar radiation.  Bright sunshine can cast shadows.  Solar radiation is “the total electromagnetic radiation emitted by the sun.”  In other words, it is the full spectrum from the smallest to the longest wavelengths.  Not all of these wavelengths are visible to the human eye, but all of them can affect our world in one way or another.  For example, bright visible sunlight makes us squint, and ultraviolet light can cause skin damage. 

Meteorologists will use the term “insolation” when considering a measure of solar radiation in a specific space.  The idea is useful in the mathematical side of the weather world where equations are used to develop models for forecasting both short- and long-term weather patterns and the effects thereof.

So, the next time you hear someone singing “You Are My Sunshine,” stop and think about how much light they’re referring to and how bright it might be.  I wonder of Johnny Cash was singing to someone whose brightness could cast distinct shadows…