Low pressure = bad weather; high pressure = good weather...WHY??

Question

How come low pressure systems bring in bad weather? is it because it sucks up the air high enough that it will cool and condense into clouds???? AND what about high pressure systems..why do they bring fair weather.

Answer 1

Yup, you are on the right track. Low presure causes rising air, which causes condensation and then percipitation. High pressure systems have sinking air, which inhibits or eliminates condensation, which causes no/little percipitation.

Answer 2

Weather High Pressure System

Answer 3

Low pressure indicates a higher per centage of water vapor in the air.
Water molecules are lighter than air. Therefore the pressure is lower.
You can probably figure out the rest of the answer for yourself.
The warm, heavier, dry air pushes into the low pressure areas creating wind.
The moist air rises (as the dry heavy air moves in below it)and cools. The moist air cools because temperatures are almost always cooler at higher altitudes. The water condenses into droplets and form clouds followed by rain, hail or snow. (Depending on temperatures and air currents.)
Dry air is by nature devoid of clouds so the warm sun shines through creating "nice" weather.

Answer 4

think convection. hot air rises right? cold air sinks.

you take up a whole bunch of air, heat it and it rises. now all that hot air took up space. so something has to fill it. so the air surrounding that area rushes in to fill that void. now because of the air rising, it lowers the pressure below the same spot.

it's the opposite for cold air, say from the artic. dense cold air stays near the ground.

all the changes in temp. and pressure causes wind. think of a really, really big whirlpool. now turn it on it's side and thats what the air is doing.

hot air carries more moisture than cold, so when you have a warm front, it usually has lots of water, ie. rain.
when the cold air comes into contact with the hot, it forces the warm air to rise. the warm air goes ontop of the cold because its lighter.
for example, oil and water. oil is lighter than water so it floats.

so when the warm air with all the moisture rises, it cools, cause it get farther away from it's heat source, the earth. when the air cools enough you get precipitation.

to answer your question, low pressure basically sucks in the air around it and rises, cool and drop te rain, snow sleet hail w/e. high pressure systems are the opposite. when air high in the atmosphere falls to the earth, because its cold dense and heavy its called high pressure. it comes down and pushes on the earth and barometers. it has already lost all its moisture content so it brings clear skies.

hope that helps explain a little bit.

Answer 5

In terms of the formation of clouds, the lower the pressure, the less moisture (water) the atmosphere can retain. The relative humidity will thus be higher at a given temperature and clouds will form with a small decrease in temperature. The opposite is true for high pressure. The atmosphere will retain more moisture at high pressures and it will require a large decrease in temperature in order for clouds to form.
Once a cloud forms, the lower the pressure a smaller decrease in temperature is required in order for rain or snow to fall.
The surrounding temperature will depend upon the air mass and the amount of heat reaching the surface of the earth.
This will partially answer your question.

Answer 6

Low pressure - the air can't hold as much H20 in vapor form so it condenses into droplets and falls from the sky.

High pressure - just like CO2 under pressure in a soda bottle, the air can absorb more H20.

Answer 7

your answer itself is better than water vapor weighs less than air??? WOW, hope you are 3.