It usually rains or will soon rain when the barometric pressure reading falls between 29.80 and 30.20 inHg (100914.4–102268.9 Pa or 1022.689–1009.144 mb).
When the barometer is rising it means that good weather is coming and when the barometer is sinking or lowering then it means that bad weather or stormy weather is about to come.
Barometric pressure, also called atmospheric pressure or air pressure, is the force or weight of the air surrounding us.
A rise in barometric pressure is generally considered an improvement in the weather, while a fall in barometric pressure may mean worsening weather.
The millibars in weather means the atmospheric force exerted on one square meter of surface.
A millibar is 1/1000th of a bar and is the amount of force it takes to move an object weighing a gram, one centimeter, in one second. c.
Millibar values used in meteorology range from about 100 to 1050.
At sea level, standard air pressure in millibars is 1013.2.
The normal range for barometric pressure is: Between 101,325 Pa and 100,000 Pa at sea level.
The weight of the atmosphere on the surface of the mercury exerts a pressure transmitted through the fluid, forcing it to rise.
The greater the weight, the higher the rise.
The barometric pressure seldom goes above 31 inches or drops below 29 inches.
Normal sea-level pressure is 29.92 inches.
Low pressure weather is when the atmosphere is relatively thin.
Usually low pressure weather means unsettled weather.
A low pressure system has lower pressure at its center than the areas around it.
Winds blow towards the low pressure, and the air rises in the atmosphere where they meet.
A high pressure system has higher pressure at its center than the areas around it.
Winds blow away from high pressure.
Low Pressure weather Typically Equals Unsettled Weather.
Locations in front of a low center (out ahead of the warm front) typically see cool temperatures and steady precipitation.
Locations to the south and east of a low center (a region known as the "warm sector") will see warm, moist weather.
In weather low pressure areas are places where the atmosphere is relatively thin.
Winds blow inward toward these areas. This causes air to rise, producing clouds and condensation.
Low pressure areas tend to be well organized storms.
Atmospheric pressure is an indicator of weather.
When a low-pressure system moves into an area, it usually leads to cloudiness, wind, and precipitation.
High-pressure systems usually lead to fair, calm weather.