Windy Community
    • Unread
    • Categories
    • Groups
    • Go to windy.com
    • Register
    • Login

    Does air pressure really affect weather?

    General Discussion
    6
    38
    4.8k
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • idefix37I
      idefix37 Sailor Moderator @vujacicm
      last edited by idefix37

      @vujacicm said in Does air pressure really affect weather?:

      Does not mean that higher is pressure, lower will be temperature?

      There is not a direct relationship between pressure and temperature at ground level.
      Let’s take 2 examples:
      In winter the Siberian anticyclone brings very high pressure and low temperatures. This thermal anticyclone is the consequence of accumulation of very cold air. The cold air is denser and it increases the air pressure.
      At the opposite the Azores anticyclone is due to the air sinking in the north part of the Hadley cell. It is a dynamical anticyclone and the sinking air is compressing and increasing the temperature when reaching the surface. When you compress a gas you produce heat.
      So, you can’t say high pressure = cold air
      In addition the temperature is not the same in all areas of an anticyclone. In this example not uniform in the vicinity of the High because the temperature at surface level is depending on the Sea temperature.

      4AC278D1-2A68-421D-9380-03FDBDFDA3CB.jpeg

      vujacicmV 2 Replies Last reply Reply Quote 1
      • vujacicmV
        vujacicm @idefix37 | Premium
        last edited by

        @idefix37 You are right. If high pressure = cold temperature, then isobars = isotermal. But because this is not the case, then this not right.

        Maybe high pressure = low temperature + high adiabatic process.

        1 Reply Last reply Reply Quote 0
        • vujacicmV
          vujacicm @idefix37 | Premium
          last edited by vujacicm

          @idefix37 I think I found answear. Pressure in poles and subtropics is the same, but height is different. Here is reason, why same pressure, but different temperature.

          1000004437.jpg

          idefix37I 1 Reply Last reply Reply Quote 1
          • idefix37I
            idefix37 Sailor Moderator @vujacicm
            last edited by idefix37

            @vujacicm
            The average thickness of the troposphere is greater in tropical areas because the average temperature is higher than in polar areas. Heating a gas, it expands.
            The temperature difference between the intertropical zones and the polar zones is due to the angle that the sun makes to the surface of the globe, and consequently the Watts per m2. Nothing else.

            vujacicmV 1 Reply Last reply Reply Quote 1
            • vujacicmV
              vujacicm @idefix37 | Premium
              last edited by

              @idefix37 What about this law? If pressure is the same and temperature increase. Then volume change.

              1000004440.png

              idefix37I 1 Reply Last reply Reply Quote 0
              • idefix37I
                idefix37 Sailor Moderator @vujacicm
                last edited by idefix37

                @vujacicm
                Yes, that’s right. It is what I said more simply : Heating a gas, it expands.
                Your question was “ I still can not understand, how north pole and Pacific have the same pressure, but different temperature? Does not mean that higher is pressure, lower will be temperature? “
                Hope it’s clear now.

                vujacicmV 1 Reply Last reply Reply Quote 1
                • vujacicmV
                  vujacicm @idefix37 | Premium
                  last edited by

                  @idefix37 So we can say like this:

                  Polar high:

                  • high pressure
                  • low temperature
                  • low troposphere

                  Subtropical high:

                  • high pressure-
                  • high temperature
                  • high troposphere

                  So, temperature and height of troposphere is different.

                  idefix37I 1 Reply Last reply Reply Quote 0
                  • idefix37I
                    idefix37 Sailor Moderator @vujacicm
                    last edited by idefix37

                    @vujacicm said in Does air pressure really affect weather?:

                    So, temperature and height of troposphere is different.

                    I would better say :
                    At global scale, the higher the temperature is, the higher is the troposphere.

                    vujacicmV 2 Replies Last reply Reply Quote 2
                    • vujacicmV
                      vujacicm @idefix37 | Premium
                      last edited by

                      @idefix37 Perfect. Now I finally understand, why 2 high pressure areas have different temperature.

                      1 Reply Last reply Reply Quote 0
                      • vujacicmV
                        vujacicm @idefix37 | Premium
                        last edited by

                        @idefix37 I found something very good, that can explain easilly

                        Charles_and_Gay-Lussac's_Law_animated.gif

                        1 Reply Last reply Reply Quote 1
                        • CaefixC
                          Caefix | Premium
                          last edited by

                          🌓 🌍 🌞 https://en.wikipedia.org/wiki/Season

                          Equator-clouds-spring.png

                          Equator-clouds-summer.png

                          Equator-clouds-autumn.png

                          Equator-clouds-winter.png

                          The troposphere gets it´s discus-shape mainly through the centrifugal force caused by Earth´s rotation.
                          If the line of equatorial clouds (= the centre of Intertropical Convergence Zone (ITCZ)) would follow the seasons, it should be expected closer to the locations of Cuba, Emirates, Taiwan in N-summer and Rio de Janero, Madagaskar - Fidschi in N-winter.

                          WheatsW 1 Reply Last reply Reply Quote 1
                          • WheatsW
                            Wheats Meteorologist @Caefix
                            last edited by

                            @Caefix This doesn't seem right.
                            The troposphere is thicker at the equator due to solar input being greater than the solar input at the poles. @vujacicm diagram shows it - as you increase temperature the air expands taking up more space. As you decrease temperature the air contracts taking up less space.

                            The tilt of the Earth and it's orbit around the Sun are what determine where that solar input is most concentrated.

                            Thermodynamically, that warm air at the equator NEEDS to make it's way to the colder poles.
                            The Coriolis Force (Earth's rotational force) helps determine the direction that equatorial air moves as it makes it's way to the poles.

                            CaefixC vujacicmV 3 Replies Last reply Reply Quote 2
                            • CaefixC
                              Caefix @Wheats | Premium
                              last edited by

                              @Wheats There´s also a vector of acceleration towards the equator balancing a centripetal vector of gravitation sucking back towards the polar vortex. Both are constants depending on latitude affecting the flow.

                              Equatorial radius
                              6378.137 km (3963.191 mi)
                              Polar radius
                              6356.752 km (3949.903 mi) https://en.wikipedia.org/wiki/Earth

                              The centrifugal force even flattens the massive globe, how could oceans and atmosphere not be affected?
                              It´s just thermo-dynamic embedded in the dynamics of the rotating system.

                              https://en.wikipedia.org/wiki/Dynamics

                              vujacicmV 1 Reply Last reply Reply Quote 0
                              • vujacicmV
                                vujacicm @Wheats | Premium
                                last edited by

                                @Wheats If I am right, then if temperature drops together with volume, then moisture will not increase. Is here then the answear, why all high pressure areas are dry, no matter of temperature?

                                WheatsW 1 Reply Last reply Reply Quote 0
                                • vujacicmV
                                  vujacicm @Caefix | Premium
                                  last edited by vujacicm

                                  @Caefix I found another thing, which is maybe very important. Different between adiabatic and isothermic. Adiabatic change pressure, isoterhmal change volume. Maybe here we can see more clear picture.

                                  1000004453.jpg

                                  CaefixC 1 Reply Last reply Reply Quote 0
                                  • CaefixC
                                    Caefix @vujacicm | Premium
                                    last edited by

                                    @vujacicm
                                    🌦 https://en.wikipedia.org/wiki/Adiabatic_process
                                    😇 https://wissen.science-and-fun.de/tabellen-zur-chemie/dichtetabellen/dichte-trockener-luft/

                                    vujacicmV 1 Reply Last reply Reply Quote 0
                                    • vujacicmV
                                      vujacicm @Caefix | Premium
                                      last edited by vujacicm

                                      @Caefix Adiabatic process works in vertical way, but not in horizontal. There is isoterhmal process. The subtropics have the same pressure like polar poles, but different temperature. There process can only be isothermall. This is main difference.

                                      CaefixC 1 Reply Last reply Reply Quote 0
                                      • CaefixC
                                        Caefix @vujacicm | Premium
                                        last edited by

                                        @vujacicm Sometimes vertical way is blocked...
                                        🏭🌫 https://en.wikipedia.org/wiki/Inversion_(meteorology)
                                        https://en.wikipedia.org/wiki/Fog
                                        https://en.wikipedia.org/wiki/Cumulonimbus_cloud ⛈

                                        1 Reply Last reply Reply Quote 1
                                        • vujacicmV
                                          vujacicm @Wheats | Premium
                                          last edited by

                                          @Wheats I think that now understand better subtropics then before. I though that desert is made because skies are clear and they rich a lot of sun. Now I see that this is not reason. Hadley cell is actually heat engine. It brings hot air from tropics to subtropics. When air reach higher troposphere, temperature drops, not heat. So heat is actually transformed like radiators in house. That's the reason, why desets are hot. In case of oceans, heat is taken by water and there temperatures are not high like in desets.

                                          The similar story is in polar cell. Polar cell is also heat engine. But when air reach the ground, all the heat is absorbed by ice.

                                          In Ferrell cell is simillar, only difference is that heat is going to north by ground, not by high troposphere.

                                          If I am not right, please fix me.

                                          WheatsW 1 Reply Last reply Reply Quote 0
                                          • WheatsW
                                            Wheats Meteorologist @vujacicm
                                            last edited by Wheats

                                            @vujacicm

                                            Global circulation cells play a big roll in climate areas on Earth.
                                            You're forgetting about moisture though - lack of moisture is the reason Deserts exist. Technically, Antarctica is a desert. But lack of moisture in subtropical desert areas can be caused by the Hadley cell that circulates warm moist air at the equator northward and southward.

                                            As the warm moist air at the equator rises it expands, cools and condenses - forming clouds and eventually precipitation...This does a few things - causes low pressure, addition of water vapour to an airmass (from the ocean in this case) will actually make the air less dense, along with the increase in temperature, the air becomes more buoyant and rises - this air is destined to rise and rain itself out. As this air moves aloft (northward and southward) it eventually becomes cool enough and dry enough where it sinks towards the Earth's surface and that's essentially where you find your subtropical deserts on continents.

                                            So the Hadley cell moves that warm (because of direct heating) equator air towards the poles.
                                            The Polar cell moves that cold (because of lack of heating) polar air towards the equator.
                                            and the Ferrel Cell is the in-between that helps get it all to where it wants to go.

                                            But this is just an overall look at Global circulation cells - there is a crazy amount going on in the Earth's atmosphere, oceans, and land, and if you are interested in learning more about it I would suggest taking a class or doing some online courses.
                                            These are two resources I used quite a lot before I actually went to school for this madness lol:
                                            https://www.meted.ucar.edu/index.php
                                            http://www.theweatherprediction.com/

                                            Read up and then please, correct me if I'm wrong!

                                            vujacicmV 1 Reply Last reply Reply Quote 3
                                            • First post
                                              Last post
                                            Windyty, S.E. - all rights reserved. Powered by excellent NodeBB
                                            NodeBB & contributors, OSM & contributors, HERE maps
                                            Terms of Use     Privacy Policy