Konstantinos
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Posts posted by Konstantinos
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If I am in an altitude about 2000 m, after 5-6 hours hiking, then my multimeter will show me my position's current atmospheric pressure. So this time how can I know the current sea level temperature and atmospheric pressure? You meant that I can see it on internet (probably with a mobile internet 3G - 4G) or I can take with me a chart prediction of it, before I begin hiking?
flyer, I created a script on matlab (name altitude) using the barometric formula from wikipedia: http://en.wikipedia.org/wiki/Atmospheric_pressure#Altitude_atmospheric_pressure_variation which calculates the altitude. Please tell me your opinion.
Code:fprintf ( 1,'Hello, I will calculate your altitude.n' );cslt=input('Please, give me the sea level temperature (degrees C):');fprintf ( 1, 'Thank you.n' );cslap=input('Please, give me the sea level atmospheric pressure (mb):');fprintf ( 1, 'Thank you.n' );cpsap=input('Please, give me the atmospheric pressure of your position (mb):');fprintf ( 1, 'Thank you.n' );alt=8.31447*(cslt+273.15)*log(cslap/cpsap)/(9.80665*0.0289644);altf= alt*3.2808399;fprintf('Your altitude is %d m or %d feetn', alt, altf);And a running of my position now:
>> altitudeHello, I will calculate your altitude.Please, give me the sea level temperature (degrees C):17Thank you.Please, give me the sea level atmospheric pressure (mb):1017.9Thank you.Please, give me the atmospheric pressure of your position (mb):999.9Thank you.Your altitude is 1.515332e+002 m or 4.971562e+002 feet>>
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Thank you johnholmes.
Hello again. A simple question: In the Barometric Formula, http://en.wikipedia.org/wiki/Atmospheric_pressure#Altitude_atmospheric_pressure_variation
if I replace the sea level standard atmospheric pressure = 101325 Pa, with the current sea level atmospheric pressure, near to my position, and the sea level standard temperature = 288.15 K with the current sea level temperature, then the accuracy will be better or badder?
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Hello flyer.
I understood about magnetic north and true north. Thank you. If I have a compass, then I can see where is the magnetic north. But how can I see where is the true north? Soon, I will take a weather handheld multimeter which can show me the true heading and the magnetic heading. How can it show me the true heading? It does not have connection with gps - satellite or mobile internet or something similar. It only has a digital compass.
I am wondering because the angle between true north and magnetic north changes and it depends on my position. For example in the center of Canada, or in the center of USA (maybe in Texas), the direction of magnetic north is the same than the direction of true north, but in Greece it is different. If you live in the straight line which begins from magnetic north and ends in true north, then you will see that the two norths have 180 degrees difference:
http://upload.wikimedia.org/wikipedia/commons/0/0a/Magnetic_North_Pole_Positions.svg
Also, I understand about the degrees and the names. To summarize, we have:
0 - 11.25 N
11.25 - 33.75 NNE
33.75 - 56.25 NE
56.25 - 78.75 ENE
78.75 - 101.25 E
101.25 - 123.75 ESE
123.75 - 146.25 SE
146.25 - 168.75 SSE
168.75 - 191.25 S
191.25 - 213.75 SSW
213.75 - 236.25 SW
236.25 - 258.75 WSW
258.75 - 281.25 W
281.25 - 303.75 WNW
303.75 - 326.25 NW
326.25 - 348.75 NNW
348.75 - 360 N
I hope I have understood it and I am right, dear flyer. -
I am trying to understand better, what is water vapor - moisture and what exactly is the saturation. When we have a sponge under the water, for example under the sea level, "it is saturated"?
Water vapor is the gas version of water? If we heat the ice (solid), we take water (liquid), and if we heat water (liquid), we take water vapor (gas)? I have understood well?
Why the air cannot take in more water vapor? What is the reason and what is the limit?
If we have two similar closed boxes, what is the difference if the one has 100% saturated air and the other has 100% water from sea? -
Ok, thank you very much. You explained clearly and I understood clearly. The last two questions:
So, I suppose, 0 degrees is the true north, not the magnetic north. Right?
When the direction is 30 degrees, we choose between NE(45 degrees) and ENE(22.5 degrees), right? So, we choose ENE because 30 - 22.5 < 45 - 30?
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What exactly is the density altitude? I have not understood it.
We say for altitude or elevation: I am 2.000 m ABOVE MEAN SEA LEVEL.
What we say for denisty altitude? I am 2.000 m ABOVE WHAT?
If I am in a mountain peak which is 2.000 m above sea level, then can my density altitude be 1.500 m? 2.000 m? 2.500 m?
Is there a formula - function which gives me the density altitude? It depends on altitude, temperature and humidity? What humidity? Absolute or relative?
Thank you.
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Here: http://www.crh.noaa....cu/humidity.php
I read this:
The dewpoint temperature, which provides a measure of the actual amount of water vapor in the air, is the temperature to which the air must be cooled in order for that air to be saturated.
I cannot understand what is the meaning of the phrase "Air is saturated". Can you explain to me?
Also, it says: Meteorologists routinely consider the "dewpoint" temperature (instead of, but analogous to absolute humidity) to evaluate moisture, especially in the spring and summer.
What is the relation between dewpoint and absolute humidity? The unit of absolute humidity is grams of water vapor per cubic meter volume of air, and the unit of dewpoint temperature is the degrees C or degrees F? I am right? The unit of dewpoint?
How dew point influences in our body's feelings?
And finally tell me about wet bulb temperature and dry bulb temperature.
Thank you.
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First question, when we say North Wind, it is reported with reference to true north or to magnetic north?
I have not understood the symbols N, NE, WNW etc. Can you explain to me them?
For example N, is 0 or 360 degrees. Right?
S is 180 degrees?
NNE?
NE?
WNW?
Explain to me please and thank you.
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Hello all. I am wondering if there are or will be jobs on internet about weather and meteorology.
I have studied Electrical and Computer Engineering and I have a good level in mathematics, control systems - control engineering and computers - programming languages.
From my young ages I have liked very much weather, and now I have decided to reach in high altitudes in mountains. Hiking and Rock Climbing are my favorite activities. So, everything says me that it is necessary to increase my knowledge in weather and meteorology.
In the near future, my plan is to improve my knowledge about weather, meteorology, dynamic meteorlology, climate etc. I will "enrich" my glossary about weather - meteorology terminology and as soon as possible I will buy a weather multimeter (Kestrel 4500 http://www.kestrelme...0-weather-meter). And I hope I will begin my adventure in mountains and rivers (I have already began).
Is there chance to find job on internet about weather and meteorology? Will the chance be increased, for the reason that I have a good level in programming languages C, C++, Java, Pascal, Matlab, Mathematica and I know Android Development? That I know Greek, English and Russian will increase it?
What is your opinion about the present and about the future (the next 5 years)? Thank you.
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Perth hits 42.1C today, but relief is finally on the way
I reminds me a week in Athens, in 2007, when we had 47 degrees during noon - midday and 42 degrees during night... I had cold shower every 30 minutes...
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I saw that the situation in India is very dangerous, with very low temperatures... 20 people died... What do you know?
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New Zealand? Auckland? What is the history of this region about tropical cyclones?
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I believe Evan will be in Sidney in a week - 10 days...
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Is it going to Australia?
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I have not understood yet. From this mathematical formula: http://en.wikipedia....ssure_variation
I can see that the altitude depends only on the pressure. Nothing else. So, if I know the pressure of my position I can find my altitude? Doesn't it depends on the pressure of my nearest sea? What is the mistake on this mathematical formula?
Or the "sea level standard atmospheric pressure" p0 is not constant?
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And what about if I am in a stable altitude, without moving, but the pressure is changing? The changes are not enough for changing my altitude?
For example now in my region I think we have 990 hPA but 12 hours ago we had 995 hPa. So?
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How an instrument calculates the altitude? Can you explain? If it knows the pressure, then how altitude is calculated? And the altitude depends on pressure? Only on pressure?
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Thank you my friends...
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Ah that's too far out yet to have any confidence things can change very quickly
Yes you are right... Thank you. But I hope the things WILL NOT change... I hope so...
Anyway, I will follow you every day...
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It certainly looks like turning colder into next week for sure depending on where you are in Europe
Athens should peak at around 17c and sunny on Monday with 14c and sunny Tuesday
Budapest is likely to be around 4c Monday and 1c Tuesday with cloud both days
Stockholm is going to be very cold with -9c on Monday and -4c Tuesday both days will see cloud and sunny spells
Kiev is also going to be cold 2c Monday and 1c Tuesday with cloud both days
Sorry, I was talking about next next week... 7 - 8 - 9 - ... - 12 December.
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What is your opinion about the cold which is coming in Central - Eastern Europe and Greece the next week?
Wind Chill Index
in Spring Weather Discussion
Posted · Edited by Konstantinos
Hello. I have created a script on matlab which calculates the Wind Chill Index (its name: Wind_Chill_Index). It uses the first formula of wikipedia: http://en.wikipedia.org/wiki/Wind_chill#North_American_and_UK_wind_chill_index
Please tell me your opinion.
Code:
fprintf ( 1,'Hello, I will calculate the Wind Chill Index of your position.\n' );tiyp=input('Please, give me the temperature of your position (degrees C):');fprintf ( 1, 'Thank you.\n' );wsiyp=input('Please, give me the Wind Speed of your position (Km/h):');fprintf ( 1, 'Thank you.\n' );wci=13.12+0.6215*tiyp-11.37*wsiyp^0.6+0.3965*tiyp*(wsiyp^0.6);fprintf('The Wind Chill Index of your position is %d degrees C\n', wci);And a simple running: