Davis
Instruments Weather Club
March 2003
In This Issue:
Virtual
Vantage Pro: Like a Video Game for Grown Ups!
Despite the
fact that we have several real live Vantage Pro consoles in various
locations around our home and office, we can't resist playing with
the new Virtual Vantage
Pro on the Davis website. This amazing bit of high-tech wizardry
lets you "push the buttons" almost just like the real thing. For
those of you considering adding a VP to your collection of cool
gadgets, you'll see just what we VP owners have been raving about!
The virtual console looks and acts so much like the real thing,
it's spooky!
Weather
Check Quiz Question 1: Can you make your Vantage Pro console
"speak" Spanish?
Triplets
Point Out Our Triple Point Error
This month's
winner of the "Most Response-Inspiring Weather Check Quiz Question"
award goes to: (drum roll here) Triple Point!
Last month we
asked, "Water is the only substance that we encounter near its triple
point everyday. What is the definition of triple point, and what
is the triple point of water?"
Our answer:
"The triple point is that temperature at which a substance can coexist
as a solid, a liquid, and a gas. At 0.01ºC, water can be ice, liquid
water, or water vapor."
Our respondents
included Rob Hale, who wrote: "Well, your definition of the triple
point lacks a key element, and we most certainly do not encounter
water near its triple point every day. Triple point is a specific
temperature and pressure at which a substance can coexist in solid,
liquid, or gaseous phase. The triple point of water occurs at 273.16
K (0.01ºC) and a pressure of 611.2 Pa. Since the pressure on top
Mt. Everest is over 30,000 Pa, this is not something we are likely
to encounter every day! Of interest, however, is that the triple
point of water is used as a standard temperature in defining temperature
scales. Thus, the temperature you gave for the triple point is exactly
(by definition) correct!"
And then Mark
Luterra chimed in with these comments: "I always enjoy your quiz
questions, as it is fun to learn more about the weather and learn
answers for Knowledge Bowl competition. It appears that the use
of 0.01ºC as the triple point of water has significant use in the
weather profession, but this temperature alone is not the triple
point, as it is impossible to convert water entirely to gas without
raising the temperature to 100ºC. The true triple point of water,
at which solid, liquid, and gas can coexist, and a small change
in temperature or pressure can convert the water entirely to one
of the three states, is: 0.01ºC and 6.12hPa. For more information
than you would like to know about the states of water, visit Martin
Chaplin's Water
Structure and Behavior website."
Well, Rob and
Mark, and all those out there who resisted the urge to set us straight
on the missing bit of information, thank you! We will say "uncle"
on the omitted pressure factoid.
But Rob, you
seem to think we were also wrong in stating that we encounter water
near its triple point every day. You assume we were talking about
Earthlings! We meant us Martians! On Mars, the atmospheric pressure
is so close to the 4.59 mmHg, that water (what do you think we Martians
drink? Martini's?) is always close to its triple point - it's quite
irritating when a glass of water almost either boils or freezes
before we can drink it.
Actually, what
we meant to say is that we encounter water daily at its triple point
temperature. But even on Earth, water exists near its triple
point temperature and pressure commonly - but only because of manmade
triple point cells used to precisely calibrate thermometers.
While most of
us do not encounter water at its triple point every day, this property
does play a role in everyday weather and everyday water behavior.
Since we have an ice-hockey player in our house, we spend hours
(many of them wee) each week watching water behave in relation to
specific pressure and temperature qualities. At every game, we enjoy
the sight of a bunch of metal blades exerting pressure on the ice
surface. The added pressure causes the ice to form a more dense
state, and in the case of water, the more dense state is liquid.
(Do your ice cubes float in your glass of water?)
Water's triple
point is a quality that determines why ice behaves the way it does
when under a metal skate blade. As Andrew Johnson of Virginia Tech's
Visual Analysis Lab, explains on his webpage: "It is the closeness
of the triple point temperature to the freezing temperature of water
that allows just a person's weight over the area of the blades to
make use of this property." Because the air pressure in the rink
is above 4.59 mmHg, an increase in pressure will cause the water
to go from solid to liquid, but not to gas.
Anyway, the
film of water thus created between ice surface and metal blade allowed
our champ to speed down the ice and score the winning goal in last
week's battle with our cross-town rivals! (Talk about pressure!
Go Bulldogs!)
(And okay,
Rob and Mark, who don't even know each other, are not triplets.
But the headline sounded much better that way.)
Weather
Check Quiz Question 2: The subject of water's triple point
having been completely exhausted, let's muck up the discussion with
yet another definition of "triple point," this time in
connection with weather fronts. How does the American Meteorological
Society define triple point? (Cheaters click here,
then search site for "triple point.")
Extra
Credit: Where does the Pa in 6.12hPa come from?
Baron,
the Canine Vantage Pro, to the Rescue!
Jim Harrington
has no need to check the temperature reported by his weather station,
because he has a professional weather dog! His beagle, Baron, broadcasts
the temperature, loud and clear, for all family and neighbors who
care to listen. Jim wrote that Baron is an outdoor dog, (don't worry,
he's a young and sturdy guy with a snug dog house), who spends his
days collecting and analyzing weather data so he can provide an
accurate evening report.
"At 30ºF, he's
quiet as a mouse," Jim told us. "At 20ºF, he's just a bit mouthy,
and as the temperature gets lower he gets really demanding. My wife
and I both work and we get back home after dark, and Baron will
tell you the temperature as soon as you get out of the car."
(Baron, we may
have a position for you on our technical staff. Send resume, with
three references including at least one from a feline.)
Weather
Check Quiz Question 3: Baron's not alone in the world of animal
weather stations. What other animal is known for its ability to
tell us the temperature? A. groundhogs, B. bears, C. crickets (yes,
they are animals), or D. dolphins.
Lordy,
Lordy, Lord Kelvin, You Were Wronged!
When we picture
one of our regular correspondents, G. David Thayer, of Salem, OR,
we can't help imagining him with a kind of a big head. How else
could he pack in all the things he knows? This time, he filled us
in on another Baron, Lord Kelvin. If you recall, two editions back
we told you that the Kelvin scale was designed so no minus signs
were needed, and last issue Mike Friese told you that the degree
symbol is also omitted in the Kelvin scale. Mike surmised that Lord
Kelvin himself didn't much care for either minus signs or degree
symbols. Well, leave it to David to know the rest of the story:
"It appears
that Lord Kelvin (William Thompson Kelvin, the first Baron of Largs)
didn't mind degree signs at all. In fact, he used them with his
proposed absolute temperature scale. The Kelvin scale was adopted
as a standard by the scientific community in 1933. Sometime much
later, in the 1960s, I believe, but surely during my stint with
the National Bureau of Standards which began in 1957 and ended in
1977, some high mucky-mucks in the scientific community decided
that the degree sign, which had been in constant use with Kelvin
temperatures up to that point, should be dropped. I no longer recall
their exact reasoning; I know I didn't really buy into it. There
is a precise one-to-one correspondence between the Kelvin and Celsius
temperature scales, with only the absolute zero point (273.15 K)
as an offset between the two. Celsius retains its degree sign, but
Kelvin lost its. Go figure!"
Who
Knows Why? Jan Null, That's Who
Dave Bastacky
of Mesa, AZ, took weather guru Jan Null up on his offer to answer
weather questions. We forwarded his question to Jan, who ran the
question and his answer in his column in the San Jose Mercury
News.
Q. Why isn't
the hottest day of the year around June 22 (summer solstice) and
the coldest day of the year around December 22 (winter solstice)?
A. The warmest seasonal temperatures are indeed four to six weeks
after the solstice. This "temperature lag" is caused by the fact
that the air is warmed not by the shorter wavelengths of solar radiation
but rather by the longer wavelengths being emitted by the earth
and other objects. The earth and oceans give up their accumulated
heat at a slower rate than it arrives and this coupled with continued
incoming solar radiation that exceeds the outgoing accounts for
the lag. Conversely the largest negative energy balance is reached
toward the end of January. Similarly this same sort of slow response
accounts for the daily maximum temperature being several hours after
noon and the daily minimum occurring shortly after sunrise.
Now you know
too! Thanks, Dave the Curious and Jan the Wise!
How
Do We Know Which Sunday is Easter Sunday?
The Easter Bunny
knows which Sunday he has to get up very early and deliver his eggs,
so that should be enough. But have you ever wondered how they decide
which Sunday Easter is each year? Although earth/weather issues
are normally more secular than this one, there is a tie-in.
The rules for
determining the date of the Christian celebration go all the way
back to the First Council of Nicaeu, convened by the Roman Emperor
Constantine, in 325 CE. Back then, they used the Roman Julian calendar.
It wasn't an easy task to set a holiday for the same Sunday throughout
the world, in a way that would be determinable indefinitely into
the future. The Council designed a series of tables to come up with
the determination, which were revised and reconstructed for several
centuries, then complicated by the fact that the Julian calendar
was slowly replaced with the Gregorian, which includes a leap year.
The short version
of the determination is that Easter falls on the first Sunday after
the first full moon that occurs after the vernal equinox. So, since
the vernal equinox has recently passed, you can just look at your
Vantage Pro to see how far away the next full moon is, and you'll
know just when to break out the egg dyes. (Remember, if you can
"cup the moon" in your left hand, it's waning; if you can "cup"
it in your right, it's waxing.)
But that is
just way too simple. First, the full moon they are talking about
is an ecclesiastical full moon, not an astronomical full moon. Though
they are more or less the same, the ecclesiastical full moon is
determined not from such wonders as the Vantage Pro, but from those
old tables, which were set up in a time when understanding the full
lunar cycle was limited. Further complications arise from the fact
that there are actually several sets of tables that determine the
ecclesiastical full moon - Gregorian, pre-Gregorian, and even one
Julian. Here's another problem: the ecclesiastical system sets the
vernal equinox at March 21, while in the civil calendar it shifts
slightly from year to year.
The end result
is that Easter doesn't always fall on the Sunday after the first
full moon after the vernal equinox. Sometimes it does. About all
we can say for sure is that since the ecclesiastical vernal equinox
is always March 21, Easter is never before March 22. Since it is
after the next full moon, it is never occurs after April 25. And
we can say this for sure: this year it's on April 11.
Check out all
the details at the US Naval Observatory's website
where you can also find an algorithm to compute the date of Easter
for any year in the Gregorian calendar system.
While you do
that, we'll be in charge of making sure the chocolate-covered marshmallow
eggs meet all our freshness standards, and that nobody ransacks
the rare, lavender Peeps.
Weather
Check Quiz Question 4: We know the moon's gravitational pull
affects the ocean. But does the moon's phase affect the weather?
Architect's
Installation Celebrates Simple Beauty of Vantage Pro Plus
Walter Scott
Perry, an award-winning California architect, is a person with extremely
good taste. He finds beauty in the utilitarian, and in those things
that align the needs of humans with the protection of our environment.
One of those things of beauty, according to Scott, is his Vantage
Pro Plus, which rises above his Hollywood Hills home's grey
and yellow garage on an elegant, accessible mast of galvanized steel
tubes and pipes, pipe fittings, turn buckles, lag bolts, and wire
rope.
Architect
Walter Scott Perry's Hollywood Hills home is beautified by an elegant
and practical Vantage Pro Plus installation.
"It is part
of a strategy I follow," Scott told us. "Beautiful design is clean
and interesting and celebrates the utilitarian. At night, my Vantage
Pro Plus is lit up and people drive by and stop to look at it and
ask about it. It gets people to think about the weather and to think
of home design that is more in concert with the environment and
energy use. It is part of a greater philosophical overview."
Scott's design
practice, EcoTech, is "dedicated to the principles of environmental
sustainability by exploring the use of low cost materials and available
technologies that can be easily plugged into existing residential
and commercial structures." He focuses on home designs that show
people how to use solar energy, and to use technology in ways that
are creative, sustainable, and visually appealing.
Scott's weather
station is part of his retrofit design of his 1950s bungalow which
includes a free-standing, 3KW solar electrical system. Scott purchased
his Vantage Pro Plus to keep him apprised of UV and solar radiation
levels to help him evaluate the productivity of his home's solar
panels.
"People used
to think solar panels were ugly," Scott added, "but as people learned
how they can save money and the planet, they became beautiful."
But Scott's
VP Plus has become much more than a way to assist in his solar energy
system. Scott's home is near the top of a ridge overlooking Laurel
Canyon, about 1300 feet above the Pacific. His weather station,
which has caught the attention of the local National Weather Service,
is one of the highest in the Los Angeles area and provides data
on some of area's intense downpours. ("We got almost five inches
in 24 hours last week!" Scott told us proudly.)
Scott's basic
philosophy of "celebrating the utilitarian" is clear in his Vantage
Pro Plus mast design. All materials were low cost and obtained at
his local home improvement store. He used galvanized steel tubes
to support the anemometer and rain collector.
"It is a very
ubiquitous material - look at just about any stop sign and you'll
see it. You can buy it at the home improvement store!"
The design allows
Scott to easily access the rain collector and temperature/humidity/radiation
sensors from his garage roof ridge. The anemometer rises another
five feet into the air on telescoping pipe which can be lowered
if he ever needs to access it. The system, guyed by steel rope for
seismic and wind constraint, has a clean, modern, nautical look.
Scott offered
to discuss creating a similar system and to share his plans with
other Vantage Pro homeowners. He can be reached via email at wspsearch@aol.com.
Weather
Check Quiz Question 5: How likely is it that Scott's Southern
California weather station will get the opportunity to report on
a hurricane?
You're
Brilliant! Answers to Quiz Questions
Question
1:
¡Si! The Spanish firmware update is available free on our
website, if you have a Davis Vantage
Pro Updater. Click here
(scroll down to Vantage Pro Firmware Spanish Text Display) to
download the new firmware and your console's ticker tape, instead
of telling you it's raining cats and dogs, will tell you it's raining
large cantaros. (And we don't mean David Wells or Randy Johnson.)
The Updater will also allow you download the latest console firmware
(in English), as well as the latest Envoy firmware.
Question
2: "Triple point: The point of occlusion where cold, warm,
and occluded fronts all come together."
Extra Credit:
The Pa is for Pascal, in honor of Blaise Pascal a scientist who
studied air pressure in the 1600's. The standard atmospheric pressure
at the Earth's surface is 101,325 Pascals. To make that easier to
read, the convention is to use hectoPascals, or 1013.25 hPa. (More
goodies on air pressure can be found at the USA Today website.
And check out the conversion charts on the NOAA's El Paso Area site.)
Question
3: While bears seem to know when it's warm enough to come out
of hibernation, they are not too keen on communicating that information
to humans. And dolphins might be smart enough to tell us, but we
imagine they are not all that interested in the air temperature.
(Where they live, temperatures tend to be more constant, regardless
of what's going on above the waves.) And groundhogs, as everybody
knows, can only tell us how far off spring is. The answer is crickets!
If you've got Jiminy or one of his cousins in your yard, count the
number of chirps he makes in 14 seconds, then add 40, then run in
and check your Vantage Pro console's reading for outside temperature.
They ought to be pretty close. (But believe the VP…)
Question
4: According to The Handy Weather Answer Book, by Walther
A. Lyons, PhD, it does. He reports that some studies show that the
Earth's lower atmosphere is 0.02ºC warmer during a full moon.
There also seems to be evidence that the moons phase affects thunderstorms,
air pressure, cloudiness, and the number of ice nuclei.
Question
5: Southern California, thanks in great part to El Niño,
is often treated to remnants of tropical cyclones and hurricanes,
which usually dissipate of the coast of Baja California. So far,
no hurricane has struck full strength in Southern California. In
September of 1997, Hurricane Linda, the strongest storm recorded
in the eastern Pacific with 180 mph winds at sea, threatened to
come ashore in Southern California. But she changed her mind at
the last minute (had she landed as a tropical storm it would have
been the first since the dramatic El Niño year of 1939) and
just dumped rain, sprouted thunderstorms, and battered the coast
with high surf. Other recent near misses include Hurricanes Kathleen
(1976) which made landfall in Baja California and treated Yuma to
57 mph winds; Olivia (1982); Priscilla (1983); and Ignacio (1997).
So there is hope (?) yet for Scott's station. Source: USA
Today Hurricane Information. Check out Linda's
bio to see how El Nino helped her grow. .
Who You Gonna Call?
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.
We think you
should know, though, that 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, such as how much cable
comes with a station contact sales@davisnet.com.
To request a catalog, you’ll find links for catalog requests
on our web site at http://www.davisnet.com/contact/catalog.asp
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 E-News. Member participation is what keeps the E-News alive
and kicking.
Well, that’s
it for this edition. You’ll be hearing from us again next month!
Vantage Pro,
Weather Monitor, Weather Wizard, WeatherLink, Weather Envoy, Weather
Echo and Weather Echo Plus, EZ Mount Gro Weather, EZ Mount EnviroMonitor,
EZ Mount Health EnviroMonitor, and Perception are trademarks of
Davis Instruments Corp
If you would like to receive the Weather Club e-newsletter via
email every month, sign up now
 |
