Furthur to my recent question and thank you Bob.
Had the 32 feet being 33 feet I would have considered this close enough to 10m.
However I now understand there are many answers to the question of the decrease in barometric pressure with height all probably correct. Taking the mean barometric pressure at sea level and at the top of Everest I concluded that a decrease in the order of 85mb per Km was about right. Although I now realise it will not be correct to divide the difference in mb by the ht in Km to arrive at a decrease that will be correct at all altitudes under all circumstances.
The figure I found on the internet of 100 mb per Km may well be correct from sea level up to 1Km in ht but for a different altitude say between 9 Km and 10 Km a figure of 75 mb per Km might be more accurate. (or is it the other way round)
Anyone ant ideas?
Thank you,
Mike.
Since this is not my area of expertise, I searched Google under the key words "'barometric pressure' altitude" to get these possible sources:
http://www.sablesystems.com/baro-altitude.html
http://en.wikipedia.org/wiki/Atmospheric_pressure
http://www.usatoday.com/weather/wbarocx.htm
http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/barfor.html
http://www.answers.com/topic/atmospheric-pressure
I hope this helps. Thanks for asking.
The problem you are faceing is this:
Trying to reduce a complicated model of reality to a rule of thumb always leads to exceptions. No matter what rule you choose, (10km per 75mb), you will find it is only a guide.
In order to accurately determine the decrease in barometric pressure with height at different altitudes, it is necessary to consider the complex factors that affect atmospheric pressure. The relationship between altitude and barometric pressure is not a simple linear relationship, and it can vary due to various factors such as temperature, humidity, and local weather conditions.
To obtain more accurate information about the decrease in barometric pressure with height at specific altitudes, it is recommended to refer to reliable sources such as scientific studies, research papers, or meteorological data. These sources provide more detailed and specific information about how atmospheric pressure changes with altitude under different circumstances.
Some useful sources that can provide information on barometric pressure at different altitudes are:
1. Sablesystems.com: This website provides information on barometric altitude and its effects on various scientific experiments.
2. Wikipedia.org: The Wikipedia page on atmospheric pressure provides a general overview of atmospheric pressure, including how it changes with altitude.
3. Usatoday.com: The weather section of USA Today provides information on barometric pressure and its variations at different altitudes.
4. Hyperphysics.phy-astr.gsu.edu: This website offers a detailed explanation of barometric pressure and its relationship with altitude, including equations and calculations.
5. Answers.com: The Answers website provides concise explanations and definitions related to atmospheric pressure and its variations.
By referring to these sources, you can gain a better understanding of how barometric pressure changes with altitude and find specific information relevant to your altitude range of interest, such as the decrease in millibars per kilometer. However, please note that the information you find may still depend on specific conditions and circumstances.