Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    Name or NavList Code:
    Email:
       
    Reply
    Anomalous atmospheric conditions and Dip correction?
    From: Tony Oz
    Date: 2021 Sep 6, 04:42 -0700

    Hello!

    Quite often there are conditions (at 60°N 30°E) that are not handled by "usual" refraction correction tables.

    This happens when the cold air is above much warmer water, and some sort of miraging appears. In less severe form - the line of sight bends upward hiding low objects on the horizon that are usually visible.

    I have two questions here:

    • how does this atmospheric condition affect the refraction at higher angles? Say, the angles more than 15°?
    • is this line of sight bending equivalent to the additional Dip, HoE change or me being further off from an observed body?

    Is it correct to say that such a bending (cold air above warm water) makes apparent Earth "more round" (i.e. of less equatorial radius)? And the opposite condition (warm air above cold water) makes Earth "flatter"?

    I need a way to understand these aspects to be able to quickly judge what the error in my intercept will be - will I be "away" or will I be "toward" - to compensate for this offset.

    Warm regards,
    Tony
    60°N 30°E

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    NavList is a community devoted to the preservation and practice of celestial navigation and other methods of traditional position-finding. We're a group of navigators, navigation enthusiasts and hobbyists, mathematicians and physicists, and historians interested in all aspects of navigation but primarily those techniques which are non-electronic.

    To post a message, if you are already signed up as a NavList member, start a new discussion or reply to any posted message and use your posting code (this is a simple low-security password assigned when you join). You may also join by posting. Your first on-topic messsage automatically makes you a member, and a posting code will be assigned and emailed to you for future posts.

    Uniquely, the NavList message boards also permit full interaction entirely by email. You can optionally receive individual posts or daily digests by email, and any member can post messages by email (bypassing the web site) by sending to our posting address which is "NavList@NavList.net". This functionality is similar to a traditional Internet mailing list: post by email, read by email, reply by email. Most members will prefer the web interface here for posting and replying to messages.

    NavList is more than an online community... more about that another day.

    © Copyright notice: please note that the rights to all messages and posts in this discussion group are held by their respective authors. No messages or text or images extracted from messages may be reproduced without the explicit consent of the message author. Email me, Frank Reed, if you have any questions.

    Join / Get NavList ID Code

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.
    Email:

    Email Settings

    NavList ID Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site