# Are low pressure and high pressure areas responsible for rain?

My understanding is that low pressure areas are susceptible to rain. However, high pressure areas have no rain. Now, I want to correlate this with the following areas -

1. Lower Hutt, Wellington , NZ - It is always windy in this region. Does it mean that Lower Hutt, Wellington has a lower pressure area and that's why it is windy? Is pressure related to the temperature here? If I go by Charles' equation - $pv = ct$, I think that the earth's position with respect to the sun causes variation in temperature and thus the pressure varies. Is my understanding correct?

2. Madhya pradesh, India - In the central part of Madhya Pradesh, India - it is extremely hot or extremely cold. Also, it rains heavily. Does it mean that the position of the earth with respect to the sun varies widely in each season? Thus, we see extreme of it in each season? Like during summer season - it builds very high pressure. However, during winter the sun shine is almost absent. Thus, it causes low pressures and finally we get rains. But, in order to get rain - we should have a high pressure nearby, right? Otherwise, how wind will flow from high pressure to low pressure? Also, sometimes rains are absent. Why does it happen? Does it mean that the high pressure wasn't high enough?

3. Bangalore, India - This is quite above the sea level and the weather is generally cloudy. It doesn't become too hot ever. Does it mean that if the area is quite above the sea level it will have a low pressure? But, there is a contrast here - like Wellington - is at a low sea level but it has the low pressure and that's why it is windy.

What concept am I missing here? Please correct my thoughts or or simplify this to me.

## 2 Answers

This is a side view in a high pressure area and low pressure area:

The high pressure air flows outward from its center (moving from higher pressure to lower pressure) and to the ground, whereas the low pressure air flows towards its center (from low pressure air to even lower pressure air). The low pressure air forms clouds when it flows towards its middle.

• How does this information relate to the questions being asked? It could use a lot more explanation and relation to the original post – Zach Saucier Jan 21 '16 at 19:02
• Unless I am mistaken, he's asking if high and low pressure are correlated with rain. I'm answering that not only are they correlated, they actually take part in causing rain – DevilApple227 Jan 21 '16 at 22:14

Pressure and rain are independent. Rain is dependent on humidity in atmosphere.

Seasons are created by change in Earths tilt towards the Sun. That's the reason why the regions close to the equator see less variation in seasons and the ones away from the equator see more variations.

Earths atmosphere is heated by the reflected heat from Earths surface. So in summer as we get more sunshine at the direct angle of incidence, there is more reflected heat from Earth surface and atmospheric temperature is hot. But that does not mean that all the places on Earth with the same latitude have the same temperature as the local geographic and environmental factors have a lot of influence. Ex. temperatures are milder at sea coasts and more extreme inland. It is generally warmer in urban and industrial locations due to higher emissions (greenhouse effect).

Winds or air currents.

Hot air is less dense, so it raises up tending to create a low pressure which pulls the surrounding air inwards. Now if the hot air has moisture in it (picked up from seas or large water bodies or even transpiration from equatorial rain forests), as it goes higher into the atmosphere (temperature drops at higher altitudes), it condenses and starts precipitating. Read about various forms of precipitation at https://en.wikipedia.org/wiki/Precipitation_types

Depending on the intensity of the low pressure it could cause different weather events. If there is air being drawn in has moisture, there could be rainfall else it would just be windy (at different speeds leading up to Tornado). So the reason wht Low pressure and high pressure are created in a certain area determine the wind flow and direction.

If you go thru how the monsoons are formed (https://en.wikipedia.org/wiki/Monsoon_of_South_Asia) you will understand why Chirapunji in the NW has heavy rainfall and Rajasthan is a desert with scant rainfall though they are on the same latitude.

• Yet low pressure systems and rain are correlated. Why is that? – Jon Custer Apr 23 at 19:40
• "Pressure and rain are independent. Rain is dependent on humidity in atmosphere." There's a problem in the reasoning here. Rain is dependent on humidity; but relative humidity also depends on pressure. – JMac Apr 23 at 20:24