Davis Instruments Search All Davis Sites
about news contact support Weather Automotive Marine

space
Davis Weather E-news
space
May 2015
In This Issue:
space
Anemometer WEATHER IN ACTION


Vantage Vue Stands Up to TWO Tornados in One Looooooong Night

This awesome shot of the supercell that produced several tornados was taken by Accuweather Meteorologist Brandon Sullivan in Stephenville,Texas, on April 26.

Quite a few of our more unlucky stations have encountered a tornado. But Michael Kennedy's Vantage Vue survived (for the most part) not one, but TWO tornados within a couple of hours!

The hearty little station has been peacefully reporting on the drought-stricken weather of Cleburne, Texas, for several years. Michael told us he bought the station because his home is far enough south of Fort Worth that most of the time the forecasts don't apply to his location.

"There is no such thing as a weather warning siren this far out in the county," he said.

But on the last weekend in April, the dry spell changed to downpours, flooding, lightning, huge hail, and reports of at least EIGHT (and as many as 19!) tornados touching down near his home. When Michael’s Vantage Vue was hit by the second tornado's 120 mph/193 kph winds and huge hail, it lost its wind cups, but otherwise didn't miss a beat.

"On Sunday, April 26th," Michael wrote, "we had been experiencing hours of 15 to 20 mph [24 to 32 kph] winds and constant thunder and lightning for almost six hours. However, no rainfall. At about 10:15 p.m. we went to bed only to be rattled within minutes by a tornado striking our property. I jumped up and ran into the kitchen and looked at my weather station console and it was showing a 121 mph [195 kph] wind with a rate of rain at 72.00 inches [1,829 mm] per hour. We experienced major property damage, but the weather station was still functioning. At about 12:30 a.m., another tornado struck our property and unfortunately this time was accompanied by large hail. My station did not perform quite as well. Two of the wind cups were sheared off by the hail."

Others were not so lucky. The tornados sheared off roofs, tossed trees onto homes, and even flipped 18-wheelers, but miraculously, no serious injuries were reported.

Michael, who is an engineer, and his family were left rattled and picking up the pieces, but impressed by the Vantage Vue's toughness.

"The remaining features worked as advertised. It was a very scary event for everyone in our rural community, but I just wanted to let you folks know how impressed I was with what your equipment was obviously designed to withstand. I assure you my next equipment purchase will also have the Davis name on it. However, if your equipment can withstand two tornados in two hours, it may be some time before I am in the market for new equipment. Thanks for producing a product that is truly worth what you ask for it."

(For a little taste of scary, check out this video taken by storm chasers Spencer Basoco and Lawrence McEwen, as their chase vehicle’s windshield is smashed to smithereens by the sudden downpour of 5” to 6” [13 to 15 cm] hail.)

 

Michael's replacement wind cups are in the mail. May they live long and hail- and tornado-free!

AnemometerWeather Check Quiz Question 1:


How fast do you think that 4” hailstone was moving when it hit the windshield?

(Click here for answers.)


Vantage Vue Helps Sharpshooters Deal with Wind

One of our favorite Olympic competitions is the biathlon, where supermen and superwomen cross country ski crazy-fast, stopping every so often to fling themselves onto the snow and shoot a rifle at a target. It was created as a way to train Norwegian soldiers, many of whom grew up skiing in the cold and wind of their beautiful homeland, maybe hunting for a little dinner along the way.

Whether in an Olympic and non-Olympic setting, anyone firing a rifle at a target on planet Earth has to take into account wind. It's a rare event when wind is non-existent, whether you are competing in a biathlon on a snowy track in Norway, hunting deer in the rain in Michigan, or shooting at targets at a sunny range in Texas. The wind will move your bullet. The question is how much and which way. The answer is in understanding the effect of wind, and in practice.

A couple of very clever Finnish innovators have created a practice system that takes all the guesswork out of shooting in the wind. Their Wind Trainer system uses Vantage Vue weather stations and specialized software to show shooters exactly how the wind will affect their shot. It even allows them to learn without shooting at all. 

Check out this video to see the system in action.

We love their motto, "Don't fight the wind, fly with it!" 

AnemometerWeather Check Quiz Question 2:


A "Full Value Wind" (one coming from either the 3 o'clock or 9 o'clock position, if the muzzle is at 12 o'clock) pushes the bullet to the right or left, respectively.

True or False: This is caused by the force of the wind on the side of bullet, just like the force of the wind on a leaf.

(Click here for answers.)

>> Back to Menu

AnemometerWEATHER 101

What in the Weather-World is a Degree Day?

Have you ever wondered just what a degree day is? Is it a day or is it a degree? Is it a day of degrees or a degree of days?

Well, your faithful Davis Weather Club E-News is here to enlighten you!

Degree days come in three basic flavors: heating degree days, cooling degree days, and growing degree days. Each of these is a measure not of days OR degrees, but of requirements. Heating degree days gives you an idea of how much heating oil you are going to require; cooling degree days give you an estimate of how much air conditioning you are going to need; and growing degree days let a farmer approximate when a crop has gotten the heat it needs to be ready for harvest.

The simplest heating degree calculation is based on the assumption that when the mean daily temperature drops to below 65°F (18.3°C), people turn on their heaters. This is the base temperature most often used in the United States, but it can be different for different buildings or locations. (In Finland, where people are made of different stuff, the heating degree day base is 63°F.)

If you take a day’s high and low, add them up and divide by two you’ll get the mean daily temperature. Let’s say this mean daily temperature was 64°F. You subtract 64 from 65 and you find that the day would be a 1 heating degree day. If you live in Barrow, Alaska, your average annual heating degree days is about 20,000. For the folks in Hilo, Hawaii, it's zero heating degree days per year. It's clear you'll spend a lot more on heating if you live in New York City (5,000 heating degree days) than Los Angeles (500 heating degree days).

Cooling degree days is the flip side of that. When the mean daily temperature rises above 65°F, people are going to need to cool off. Find the day’s mean temperature and subtract 65 from it. A mean temperature of 72 would have a cooling degree day of 7. If you work at the power company, you will be able to directly relate that 7 to an up tick in energy usage.

Degree days are useful because you can add them up to get weekly, monthly or yearly degree days. That number can be more useful than, say, an annual average temperature, because it accounts for all the variations in temperature over each day of the year. A composite of heating and cooling degree days gives a good indication of the energy requirements over the year. 

Engineers and architects use average heating and cooling degree days of a location when they design buildings. It helps them decide what kind and how much heating and air conditioning will be needed, and how to best insulate to maximize the energy consumption.

Here's a more in depth discussion of degree days and energy consumption on Bizee Energy Lens.

If you have a Vantage Vue, you can see your heating and cooling degree days in the Weather Center on your console. If you have a Vantage Pro2 you can see heating and cooling degree days in WeatherLink.

Growing degree days are a whole different index, but once you understand heating and cooling degree days, the concept is easier to grasp. In order to grow to maturity crops need water, good soil, fertilizers, pest and disease control, sunlight and, very importantly, HEAT. Each crop's need for heat to reach maturity is different.

Farmers can use a specific base temperature (such as 50°F for Sweet Corn or 60°F for Delta Smooth Leaf Cotton) and the crop’s estimated degree days to maturity (2200 - 2800 for Sweet Corn; 1900-2500 for Delta Smooth Leaf Cotton) to get a good indication of when crops are ready for harvest.

Growing degree days are also useful to growers because they can be used to determine when an insect or disease risk is high. They can help a farmer know what crops to grow in any location, control weeds, and time fertilizer and pesticide application.

So the next time someone stands up and shouts, "Help! Does anyone here know what a Heating Degree Day is?" you can be a hero.

2014 Beat 2013 in Weather Catastrophes

Climate change is pretty much all bad news. This article in Breaking Energy tells us that in 2014, "92% of the loss-related natural catastrophes were weather events." It also has some comparison maps of the world with "loss events" in 2014 and 2013. (Yes, 2014 was worse.) But the most alarming visual aid in the article is one that shows a steady, relentless increase in the number of natural disasters from 1980 to 2013.

But the article has a couple of little glimmers of good. For one thing, fewer people are dying due to these events. That's because we've gotten better at early warning systems, especially for hurricanes. For another, Germany generated more wind power from its wind turbines in the North and in the North Sea than any other month before.

Oh. Yay.

AnemometerWeather Check Quiz Question 3:


Which one is not a real moon phenomenon?
A. Moon Dog
B. Moonfrost
C. Moon Halo
D. Moon Storm
E. Moon Pillars
F. Moonbow

(Click here for answers.)

>> Back to Menu

AnemometerTECH TIPS

A Maintained Weather Station is a Happy Weather Station

Vantage Vue and Vantage Pro2 integrated sensor suites (ISS) are built to stand outside night and day, unshaded from the hot sun, dumped on by snow, whipped by high winds, inundated with rain. We build them to not only do this without a hitch, but to do it for years. Today is a good day to thank your intrepid weather station (and send a little love to our engineers) by giving it the weather station equivalent of a spa day. Here’s a handy checklist of ISS maintenance tasks:

Vantage Vue ISS:

  • Rain Collector: Peer into your rain collector cone to make sure it is not clogged with leaves, bird droppings, or other debris. Wipe it down with a soft, damp cloth.
  • Remove the tipping spoon assembly by loosening the thumbscrew that holds it in place on the underside of the ISS. Clean with a soft, damp cloth, being careful not to scratch the surfaces. (Be sure to clear any false rain readings you create when removing and replacing the tipping spoon assembly.)
  • Spin your wind vane and cups. Make sure they move freely. (Never use lubrication on your anemometer!)
  • Wipe down the radiation shield if it is dusty or has any insects or debris.
  • As needed, disassemble your radiation shield and thoroughly clean it. We recommend once a year, but that is just a guideline. If your station is in a particularly dusty, buggy site, it will need a thorough cleaning every year. If it is not, you can go longer between thorough cleanings without affecting accuracy.
  • Sometimes the glass over the solar panel becomes frosty looking. This will not affect your weather station's performance at all.

Vantage Pro2 ISS:

  • Rain Collector: Check your rain collector cone to make sure it is not clogged with leaves, bird droppings, or other debris. Remove the cone and wipe it down with a soft, damp cloth. Clean the tipping buckets with a soft cloth, being careful not to scratch the silver coating. (Be sure to clear any erroneous rain data you cause by tipping the buckets.)
  • Spin your wind vane and cups. Make sure they move freely. (Never use lubrication on your anemometer!)
  • Wipe down the radiation shield if it is dusty or has any insects or debris.
  • As needed, disassemble your radiation shield and thoroughly clean it. We recommend once a year, but that is just a guideline. If your station is in a particularly dusty, buggy site, it will need a thorough cleaning every year. If it is not, you can go longer between thorough cleanings without affecting accuracy.
  • Transmitter shelter: Open the shelter and make sure there are no insects or nests inside it. Make sure all sensor cables are plugged in and that the foam insert is snuggly inserted in the access port.
  • Sometimes the glass over the solar panel becomes frosty looking. This will not affect your weather station's performance at all.

AnemometerWeather Check Quiz Question 4:


What do you do if your console displays this message:
LOW BATTERY STN 1

1. Put new C-cell batteries in your console.
2. Put a new 3-volt lithium battery in your ISS.
3. Call the British National Rail System and inform them that the battery at Stonehaven (STN) railway station is low. Or maybe it’s the battery at Stansted Ariport...

Extra Credit:
True or False: The solar panel recharges the lithium battery in the ISS.

(Click here for answers.)

>> Back to Menu

Anemometerdavis in the news

Young Meteorologists From Victoria Island to Hampshire


Quadra Elementary School principal Marilyn Campbell with a classroom Vantage Pro2 console. Photograph by Adrian Lam, Times Colonist. Used with permission.

Everyone on Vancouver Island seems to know that it is colder in James Bay and Fairfield than it is in the rest of Greater Victoria. Researchers at the University of Victoria are looking into why, and they have drafted a whole army of young research assistants. The students at the 150 schools comprising the School-Based Weather Station Network are gathering and analyzing data for the study at "UVic."  Check out the story in the Times Colonist.

If you walked/swam about 6,000 miles/10,000 km due east from Victoria Island, you might come to group of students looking at a Vantage Pro2 or a Complete Soil Moisture/Temperature Station at Hampshire Collegiate School in Hampshire, UK, as featured in this case study. The students in years 7 through 13 are using the data from the station in their classrooms as they study weather, climate and plant growth.

We love this line from the study: "A Davis weather station was chosen rather than a domestic station for its professional quality. It is better constructed and a more robust station which was vital to the staff as the weather station is located in the middle of the school golf course." (Golf course? Now that sounds like a fun school!)

AnemometerWeather Check Quiz Question 5:


Vancouver is known for The Grind. What is it?

A. An almost two-mile (3 km) stone staircase up a mountain.
B. A hip coffee shop that features hourly indoor rain showers.
C. A modern sculpture created from an antique mill wheel that stands in a small park at the intersection of “Van” and “Couver” streets.
D. What Vancouverans lovingly call winter, when the days can be wet and gray.

(Click here for answers.)

>> Back to Menu

AnemometerMail Bag & I Spy a Davis Station

You Call it a Brown Cow, They Call it a Black Cow

Greg, who's Vantage Pro2 Plus is reporting 90°F/21°C, with gentle breezes on the beach in Aguadadilla, Puerto Rico, used to work in an ice cream shop. So that is why the Penn State creamery calling a vanilla-and-root-beer flavored ice cream a "black cow," as we reported in our last issue, really bugged him.

"That is a brown cow," states Greg. "A black cow is cola (such as Coke or Pepsi) and vanilla ice cream. Root beer is brown, cola is black - hence the distinction."

Thank you, Greg. You can call it any color cow you want if we can drink it on your beach!

A Very Lenticular Backdrop


Franck Feuillade posted this pretty photo on our Facebook page of a lenticular cloud providing a backdrop for his double-header anemometers on Reunion Island.

Fast Cars and Big Aircraft

Brad A. spotted a Vantage Pro2 while watching a documentary on developing the 2015 F1 race car for the Mercedes Petronas Racing Team.

"I saw a nice close-up of the weather station at the famous Silverstone Raceway on the first test drive of the car filmed this past winter. Snow started falling on the anemometer so they packed up and left. Not sure if it belonged to the team or the track. Their top driver, Lewis Hamilton, is the reigning 2014 F1 Driver Champion and Mercedes is the 2014 Manufacturers Champion."

Good spot, Brad!

Sharp-eyed William Vigotty spotted a Vantage Pro2 on a Fox News story, "Meet the World's Largest Aircraft" about the huge Airlander. (Maybe Fox saw it here first?)


 What do you think of the E-Newsletter? How can we improve? How do you use your Davis weather products? E-mail us at news@davisnet.com.

IconANSWERS TO QUIZ QUESTIONS

Question 1: How fast do you think that 4” hail was moving when it hit the windshield?

As that video shows, it was moving FAST. It’s estimated that a 1 cm (.39 mm)  hailstone falls at  20 mph. An 8 cm  (3.19 inch) stone would hit at over 100 mph.

The velocity of hail is a complex thing to figure out. It is affected not only by gravity, but by wind, friction, collisions with other hailstones, and by the nature of hailstones (as opposed to, say, a baseball, or a baseball-sized chunk of steel). If you are of the nerdy persuasion (our favorite kind of persuasion), check out this analysis, “Big Hail is Bad” by Rhett Allain in Wired.

>> Back to Menu

Question 2: True or False: A "Full Value Wind" pushes the bullet to the right or left, respectively. This is caused by the force of the wind on the side of bullet, just like the force of the wind on a leaf.

We know you said false, because it seems so simple, and nothing in the world of weather is ever simple! This statement would be true if a speeding bullet was anything like a leaf. But a bullet is not like a leaf. For one thing, it is moving, and it is decelerating. It also has a specific shape that causes it to point very slightly into the wind (think of your bullet-nosed wind vane). It is not pushed, but deflected. Imagine drawing the trajectory of a bullet, fired in a constant crosswind, from the muzzle to the target. If the wind simply "pushed" the bullet, the trajectory would be a straight line traveling at an angle out from muzzle. But the actual trajectory of that bullet is a curve: a deflection, not a push. More on this can be found in this Shooting Times article. 

And just to make it a little more FALSE, the force of wind on a bullet causes it to move not only laterally, but slightly up and down as well. So if you shoot directly into the wind (a 6 o'clock wind), which would have no "pushing" effect on the sides of the bullet, your bullet may still be moved by the wind.

>> Back to Menu

Question 3: Which one is not a real moon phenomenon?

Nah to Moonfrost. Made it up.

Yes to Moon Dog: Bursts of light on both sides of the moon, caused by ice clouds in the atmosphere.
Yes to Moon Halo: A ring appearing around the moon from light passing through ice crystals.
Yes to Moon Storm: A long, skinny storm that most scientists say swirls night and day on the dividing line between lunar day and night.
Yes to Moon Pillars: Pale shafts of light extending out above or below the rising or setting moon.
Yes to Moonbow: Like the song goes, "Somewhere, over the moonbow...which is like a rainbow...only it's made by refracted moonlight instead of sunlight.." To get a moonbow, the moon has to be low and full, the sky has to be dark, and you need water droplets in the air. Even then, the colors in a moonbow are very hard to see -- so you also need a camera set for a very long exposure.

>> Back to Menu

Question 4: What do you do if your console displays this message: LOW BATTERY STN 1?

Put a 3-volt lithium battery in your ISS!  If you need to replace the batteries in the console, the message will read “LOW CONSOLE BATTERIES.”  (Note that you will also see this low console batteries message if you have no batteries installed and are running the console on AC power.)

Extra Credit: True or False: The solar panel recharges the lithium battery in the ISS.

False. The lithium battery is not rechargeable. The solar panel powers the station during the day, while the battery powers it at night or when sunlight is low. Since the lithium battery is a backup for the solar panel, in most installations it should last for years.

>> Back to Menu

Question 5: Vancouver is known for The Grind. What is it?

A. A stone staircase up Grouse mountain that athletes of all ages haul themselves up. Known as “Mother Nature’s Stairmaster," it offers such hearty folk a two-hour hike that climbs 2,800 feet (853 meters) in 1.8 miles.

>> Back to Menu

AnemometerWHO YOU GONNA CALL?

Davis!
Each month after the E-News goes out, we receive messages back. Sometimes the messages are in response to a story we shared; other times they are a request for help of some kind. We read all the emails, answer those we can, and pass the rest on to the appropriate departments. If you're interested in the fastest possible reply, news@davisnet.com may not be the best place to send your message. Questions about how things work should be addressed to tech support directly at support@davisnet.com. For general information about the products, contact sales@davisnet.com. To request a catalog, see the links for catalog requests on our web site at www.davisnet.com/contact/catalog.asp.

What do you think of our E-news? Please continue to send your comments, weather URLs, and story suggestions to news@davisnet.com. We look forward to getting your comments and any responses you have to the Davis E-News. Member participation is what keeps the Davis E-News alive and kicking.

Well, that's it for this edition. You'll be hearing from us again next month!
If you would like to receive the Weather Club e-newsletter via email every month, sign up now.

The Davis Weather Club E-Newsletter is published by Davis Instruments.

Vantage Connect, Vantage Vue, Vantage Pro2, Vantage Pro2 Plus, Vantage Pro, Vantage Pro Plus, Weather Monitor, Weather Wizard, WeatherLink, WeatherLinkIP, Weather Envoy, and Perception are trademarks of Davis Instruments Corp.

space