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FREQUENTLY ASKED QUESTIONS | ||
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GENERAL
Q. Does the WeatherCam system run 24/7?
A. Yes, the system runs continuously.
CAMERAS
Q. Sometimes I notice the two 'looking out to sea' cameras are blurry and
other days they are perfectly clear. What's wrong with the cameras?
A. Is this an example of what you mean?
There's actually nothing wrong with the Cams! This 'issue' manifests itself
due to the Yacht Club being on the beach and the cameras are getting a build
up of salt on the lenses due to high winds from the direction of the water.
Sometimes rain associated with the high winds/storms will fix this 'automatically'
but the lenses will more than likely need cleaning. There are nearly always
people around the Clubhouse and the lenses will certainly get cleaned as soon
as possible.
Q. When I log on I only see still images. Is this correct or is my browser
not setup properly?
A. Yes, this is correct and still shots are normal.
The image array is updated every minute and you should refresh regularly to
get the latest images.
Q. Will there be a full motion live stream from the cameras?
A. No it will not be motion video. It should be said
that whilst the system is capable of outputting up to 6 frames per second,
this would have a very significant impact on both the network at FYC, so the
system has been setup to run only 1 frame per minute. Full motion is also
extremely hungry on your download usage!
Q. Do the images automatically update for me?
A. No, the code behind the system could do this automatically,
but this process would have a detrimental effect on users with slower connection
speeds - these users would likely not see anything at all as their system
would spend the whole time trying to download images...which they would never
see as they keep changing before they finish downloading! Experience also
tells us that people like to site and look closely at the data.
Q. When I refreshed earlier, only two pictures came up and the third box
had a 'broken link' icon in it. Is there an intermittent camera system fault?
A. No it's not faulty. When your browser refresh occurred
the camera system was in the process of updating the Server with a new set
of images. Refresh your browser to fix this.
Q. Sometimes the brightness and contrast varies between the cameras. Is this
a fault with the camera?
A. No, this is not a fault - just an electronic function
of the cameras that cannot be overridden. The cameras each control their own
exposure and color balance, and sometimes one cameras frame may have a significant
difference to the others for reasons such as the morning sun, reflections
and even cloud cover in various parts of each shot will also affect the exposure.
The afternoons display the most consistent array as the sun is behind the
cameras.
WEATHER AND GRAPHS
Q. I noticed this morning that the wind direction indicated in the data did
not seem to be the same as where the boats were pointing.
A. If you consider a windex or telltale on any boat
and you'll notice that it never sits still. Even if the wind is hard out of
the SW - it will continually bounce around, but in real time, your perception
is clearly that it is hard in the SW.
So to understand the apparent discrepancy with the boats direction and reported wind direction, it's important to note how the system actually assembles data for the site. The Weather Station takes a snapshot which lasts for less than half a second, and it is possible - more likely probable - that the wind direction vane was being buffeted around as they all do when the snapshot was taken.
Another point of interest here is that if the wind speed is read as zero by the system, the wind direction will not be updated. So if a light zephyr manages to turn the boats without spinning the anemometer cups, the instrumentation will not reflect the direction shift until the anemometer is moving again.
This oscillations, which are perfectly normal, appear
averaged out using the Wind Dir chart and although the oscillations are present,
it becomes very easy to recognise the predominant direction.
Q. What is the 1 minute average and graph all about?
A. There are several items of interest here. Firstly,
the graph is a very high detail snapshot of the the last 5 minutes showing
all the fluctuations in speed for the period. The right hand side of the graph
is the most current and the left hand side is 5 minutes ago. The text at the
top of the graph shows the current wind speed at the time the data sample
was grabbed and the lower left corner shows us the mean (or average) speed
for a 1 minute duration during this period while the trace line shows the
exact data for the whole 5 minute period. It also notes the peak gust for
the 24 hour period in the lower right corner.
Q. The new graphs seem to have scales that might be exceeded. What happens
if it blows over 25 knots?
A. The graphs are auto scaling and the vertical axis
will dynamically change as needed. If a bullet comes through, the chart may
not shift the scale up until there is a bit more steady pressure at that speed
range. The auto scaling will occur on all graphs and in the case of the barometric
pressure will lower the scale as necessary too.
Q. There are spikes and lines everywhere. Why does it draw from top to bottom
like that?
A. The best way to answer this is to study a screen
grab.
The above example shows some of the behavior you are talking about. Let's start at the left hand side of the graph. At 10pm we had a quite steady breeze from the East (our evening Sea Breeze) at about 6 knots and an outside temp of approx 15 degrees.
Just after 11pm, the breeze started to decrease and turn toward the North. The breeze fluffs up and down from zero to 4 knots for the next hour, then dies out completely at 12.00. The direction indicator then parks at the last reading until the breeze returns.
At approximately 12.20am, a light 5 knots fills in from ESE until 1.30am when it drops out completely again for nearly an hour. At 2.30am the breeze fills in and progressively builds from the North. The huge trace-line oscillations on the graph represent the breeze swinging through North to the NNW and back through North to the NNE. You must consider that that this line graph is displaying all bearings on the compass rose, and consequently North appears at the top and the bottom of the chart.Therefore as mentioned, as the breeze passes through North, it will re-appear either at the top or bottom of the graph depending on the direction shift.
At about 3am, it settles in direction in the NNW and continues to build.
The remainder of the graph shows the breeze is flukey and gusty. If we were to determine a trend for this period, it would be that when the breeze softens it clocks left, then as the speed increases, it clocks right to the NNW again. Between 7am and 9am is a good indication of this trend.
Notice at about 2.10am the wind dies out and turns toward the North and the temperature, not surprisingly, increases. The barometer is dropping through this period.
Q. The direction graph is full of red - what's that all about?
A. I assume you've seen something like this an wondered
if there may be something wrong..
No there is nothing wrong with this at all - although it might appear a bit odd at first glance. You need to consider that a compass rose is 360 degrees - and a circlular representation, where 0 and 360 are the same thing.
When you create an X/Y graph like this one, then there must be a top and a bottom to it - in this case 0 and 360....but these are the same point on the compass!
So in the context of this picture, it is telling us that the wind is hard out of the North (0 or 360 degrees) and is crossing through this point continuously to become NNW or NNE. The line trace does not 'lfit up off the paper' and stop drawing as this passing through 0/360 happens. In the image, just after 4am the breeze sat in the NNW for nearly an hour.
Q. On the graph explaining the red trace line going top to bottom all the
time can you please explain why the small chart above it shows that it is
blowing easy 35-40, but the current wind speed is only 28.3 knots?
A. This graph is a 5 minute view and the current wind
speed reading is an instantaneous snapshot at the time of the system data
gather process. Therefore, in this case, there was clearly a brief lull or
some buffeting etc that slowed the speed down when the snapshot was taken.
So I suggest that in this instance it is more appropriate to read the 1 minute average value - which takes all of the pressure you are talking about - gusts and lulls and all and produces an average for the last 1 minute. This produces a reading more consistent with the 'overall picture' than the snapshot does.
Systems Integration of Lighting, Sound,
Video and Computer Display Solutions
Web based Control Solutions.
AMX Control System Specialists.
www.stephenboltonassociates.com