The Pressure Impact from Higher to Lower Altitudes

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. In this blog we’ll discuss pressure and the difference in impact from high to lower altitudes.

The Pressure Impact from Higher to Lower Altitudes

If you have ever driven from a high altitude, say 5000’ above sea level to about 1000’, and you have a flexible sealed empty bottle in the car, at some point, you notice the creaking sound as the bottle collapses due to lower atmospheric pressure sealed inside and higher atmospheric pressure outside.  With the sound effect, the pressure increase on the sealed bottle taken from higher to lower altitude is quite noticeable. Obviously the pressure decreases (externally) during the reverse process and a gas tank (or other similar sealed vessel) taken to a higher altitude winds up visibly expanding.

post25

This is just one example of the impact of altitude pressure. Athletes performing at higher altitudes know that the altitude affects their performance, especially their endurance, since high altitude (HA) causes faster and deeper breathing. Altitude also affects sleep and cardiac output, so those accustomed to living at lower altitudes need to take appropriate precautions to adjust to the change. Training at higher altitudes can actually enhance the performance of athletes when they compete at lower altitudes.

Humans aren’t alone in their need to adjust to altitude. Internal combustion vehicles must adjust to altitude as well. When electronics was first used to adjust spark and fuel to reduce emissions and improve fuel economy, carmakers used barometric pressure sensors to adjust for altitude.

The pressure change from one altitude to another can be calculated by calculating the pressure for each altitude and then subtracting.  Air pressure above sea level is:

p = 101325 (1 – 2.25577 10-5 h)5.25588

where,

p = air pressure (in Pa)

h = altitude above sea level (in m)

What do you think/Comments?
Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
-Han Mai, Marketing Coordinator, All Sensors Corporation ([email protected])

Welcome to All Sensors Blog

Welcome to All Sensors “Put the Pressure on Us” blog. This blog will bring out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. This initial blog explores pressure sensing in weather measurements.

Barometric or air pressure – either rising or falling – indicates a change in weather and is usually included in weather reports with temperature, rain or snowfall and wind measurements. While the temperature, rain and wind information is quickly verified by just going outside, the pressure measurement is a longer term issue. The absolute pressure measurement in inches of mercury for the U.S. is typically about 30.00 for a steady reading depending on height above sea level. The rate and amount of a falling barometer indicates how quickly a storm will occur and its severity. Barometric pressure change may be several days or only a few hours before the weather front. Accurate and precise pressure measurements need to consistently resolve a rather small pressure range since the pressure drop or rise from a steady barometer is usually within 00.20 inches of mercury.

What do you think/Comments?
Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
-Dan DeFalco, Marketing Manager, All Sensors Corporation ([email protected])