Barometers

Atmospheric pressure is commonly measured with a barometer. In a barometer, a column of mercury in a glass tube rises or falls as the weight of the atmosphere changes. Meteorologists describe the atmospheric pressure by how high the mercury rises.

Pascals

Barometer, device used to measure atmospheric pressure. Because atmospheric pressure changes with distance above or below sea level, a barometer can also be used to measure altitude. There are two main types of barometers: mercury and aneroid. Mercury barometer.

Calculating pressure

1. To calculate pressure, you need to know two things:
2. Pressure is calculated using this equation:
3. pressure = force ÷ area.

Atmospheric pressure is the pressure caused by the mass of our gaseous atmosphere. It can be measured using mercury in the equation atmospheric pressure = density of mercury x acceleration due to gravity x height of column of mercury.

Example – Air pressure at Elevation 10000 m

Pressure with Height: pressure decreases with increasing altitude. The pressure at any level in the atmosphere may be interpreted as the total weight of the air above a unit area at any elevation. At higher elevations, there are fewer air molecules above a given surface than a similar surface at lower levels.

Pressure was defined to be force per unit area. This equation tells us that the pressure exerted by a column of water is directly proportional to the height of the column and the density of the water and is independent of the cross-sectional area of the column.

The density of sea level is higher and as a result due to the high density of sea level, atmospheric pressure is maximum here. At higher altitudes, fewer number of gas molecules means or refers to fewer molecular collisions and thereby decreasing atmospheric pressure.

A barometer reading of 30 inches (Hg) is considered normal. Strong high pressure could register as high as 30.70 inches, whereas low pressure associated with a hurricane can dip below 27.30 inches (Hurricane Andrew had a measured surface pressure of 27.23 just before its landfall in Miami Dade County).

Barometric pressure is the weight of the atmosphere that surrounds us. Barometric pressure often drops before bad weather. Lower air pressure pushes less against the body, allowing tissues to expand. Expanded tissues can put pressure on joints and cause pain.

Reduced air pressure means that there is less oxygen available to the body. This means that for every lungful a climber breathes there will be fewer oxygen molecules going into the bloodstream.

The air pressure in your lungs has to be less than the air outside your lungs, to get your lungs to inflate. This is because air moves from high-pressure areas to low-pressure areas. During bad weather and at high altitudes the air pressure is lower, making it harder for us to breathe.

A drop in atmospheric pressure, as observed at high altitudes, leads to decreased oxygen saturation. The effect of regular changes in barometric pressure at sea level has never been studied in a general population.

Specifically, we found that the range from 1003 to <1007 hPa, i.e., 6–10 hPa below standard atmospheric pressure, was most likely to induce migraine.

Vanos said people are most comfortable with barometric pressure of 30 inches of mercury (inHg). When it rises to 30.3 inHg or higher, or drops to 29.7 or lower, the risk of heart attack increases.

Feels like: An intense, throbbing pain, often one side of the head. The pain is often accompanied by symptoms like nausea, vomiting, sound and light sensitivity, and auras. Auras are changes in vision, speech, and other sensations. They occur before the migraine starts.

High-Pressure Headaches (IIH) The symptoms of a high-pressure headache often mimic those of a brain tumor, which is why IIH used to be called “pseudotumor cerebri,” or “false brain tumor.” Those symptoms include: Migraine-like or throbbing pain that’s often worse in the morning. Neck and shoulder pain.

Effective treatments to reduce pressure include draining the fluid through a shunt via a small hole in the skull or through the spinal cord. The medications mannitol and hypertonic saline can also lower pressure. They work by removing fluids from your body.

These are the most common symptoms of an ICP:

• Headache.
• Blurred vision.
• Feeling less alert than usual.
• Vomiting.
• Changes in your behavior.
• Weakness or problems with moving or talking.
• Lack of energy or sleepiness.

The normal range for CSF is reported differently in various sources, with most reporting a normal range of 7-18 cmH2O in adults,1 though some consider the normal range 5-25 cmH2O. However, a pressure >25 cmH2O or <5 cmH2O should certainly prompt you to look for a source.

Intracranial hypertension means that the pressure of the fluid that surrounds the brain (cerebrospinal fluid or CSF) is too high. Elevated CSF pressure can cause two problems, severe headache and visual loss. If the elevated CSF pressure remains untreated, permanent visual loss or blindness may result.