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incubus
Joined: 29 Jun 2005
Posts: 1
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| Posted: Wed Jun 29, 2005 10:00 pm Post subject: ATIS clarification |
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| When you are listening to the ATIS, they tell you the outside temperature, followed by "dewpoint #". What does this mean? |
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brettr10
Joined: 15 Jun 2005
Posts: 77
Location: Banbury, Oxfordshire UK
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| Posted: Wed Jun 29, 2005 10:25 pm Post subject: |
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| dewpoint is the temperature at which a parcel of air becomes saturated if it cools (at constant pressure), i.e. the temp at which it is no longer able to support all of the water vapour that it contains; the more moisture in the air, the higher its dewpoint temperature. I hope that helps. |
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Max
Joined: 10 Dec 2004
Posts: 673
Location: LQSA
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| Posted: Wed Jun 29, 2005 10:27 pm Post subject: |
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ATIS gives you two informations in most cases and it is:
METAR report and Runways in Use
A "METAR" report is a weather report and consists of thye folowing:
LYBE 300030Z 12008KT CAVOK 25/14 Q1012 NOSIG
meaning
LYBE Belgrade Airport
300030Z means that the report is deom 30th Day in current month and from 0030 zulu
12008 means thw ind in at 120 degrees and 8 knots in speed
CAVOK means Clouds and Visibility Okay
25/14 means Temperature is 24 Centigrade and dewpoint is 14 centigrade
Q1012 means QHN (Local Altimeter setting in milibars)
NOSIG means no significant changes expected
That is all :) |
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ricktobin
Joined: 21 Feb 2004
Posts: 1646
Location: Virginia Beach, Virgina USA (KNTU, KORF)
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| Posted: Wed Jun 29, 2005 10:53 pm Post subject: |
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Incubus, you asked a simple question and got two completely different answers. To clear it up, brettr10 gave you the correct answer.
...and why is the dew point reading necessary:
In the real world the difference between the dew point (the temperature to which air, at constant pressure, and water vapor content must be cooled for saturation to occur) and the temperature is used to predict fog formation. The smaller the difference between the temperature and the dew point, the greater the possibility of fog formation. Fog decreases the visibility of pilots. |
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Max
Joined: 10 Dec 2004
Posts: 673
Location: LQSA
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| Posted: Thu Jun 30, 2005 8:59 am Post subject: |
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#-o Doh, I thought he was asking what do all if them mean :oops:
Now that I have read the question a few times over...I realised, I have made a completely pointless post 8O |
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brettr10
Joined: 15 Jun 2005
Posts: 77
Location: Banbury, Oxfordshire UK
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| Posted: Thu Jun 30, 2005 9:58 am Post subject: |
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| lol Max! Your plane got ahead of you that time you must have been tired. |
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wheelright
Joined: 15 May 2004
Posts: 169
Location: KDNL/KAGS
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| Posted: Thu Jun 30, 2005 3:45 pm Post subject: |
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Quote: used to predict fog formation
Also, the dew point is a factor in the the possibility of icing. |
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brettr10
Joined: 15 Jun 2005
Posts: 77
Location: Banbury, Oxfordshire UK
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| Posted: Thu Jun 30, 2005 3:53 pm Post subject: |
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| absolutely wheelright, water has 3 latent states ice, liquid and vapour. Icing occurs when the temperature inside the cloud is lower than the air around it. Water can exist in it's liquid form down to as low -30c or -40c and even colder, this is super cooling. So as soon as it touches say a metal airframe it turns to Ice. |
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