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Thread: How To Make Wind and Influence Climate

  1. #1

    Wip How To Make Wind and Influence Climate

    I am trying to work out the climate of the world that I am working on. While climatology interests me I still don't know much about it. If some of you could take a look at what I have done it would be greatly appreciated.

    Using the conic graticule provided by Hai-Etlik I have determined the relative air currents, and with the help of Hawksguard and Juggernaut1981 my mountains are in place. I have included a map with wind currents, rain shadows, and areas where deserts should occur. Or at least I believe they should occur.

    The ranges are labeled 1-7 (with 1 being the oldest mountain range). 1-4 are ancient, 5a-5c are middle-aged, and 6 & 7 are the youngest (and the highest with 6 being massive). I do know that mountains force air upwards, cooling the air, and causing precipitation, but that is where my knowledge ends.

    The yellow areas are proposed deserts, the red areas are rain shadows created by the mountains, and the red 23 near the center is the 23rd parallel. Any area below this line is going to receive rainfall to varying degrees, and in many places excessive rainfall. The deserts are not in their final form. They are approximate and representative.

    If you have any ideas about what I have done so far I would to hear it. I also have a few specific questions:

    1. When mountains force precipitation can the water fall in catchments and create rivers on the opposite side (where the shadow lies)?
    2. Do you see any area where the weather might be particularly volatile?
    3. Hurricanes will form in the southern oceans, but at what latitude do they usually form? Will hurricanes/typhoons cross the equator?

    Click image for larger version. 

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    Again I could not insert the image online. I don't know why. Sorry about that.

    Once I determine the rainfall and wind I will begin work on the water currents and distribution. I didn't want to do too much at once. Thanks in advance for any help.
    "I run away, therefore I am." - Monty "the Python" Descartes

  2. #2
    Guild Expert jbgibson's Avatar
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    Hey, Porklet. I'm no climatologist, nor do I play one on TV. Nonetheless, like you, I'm interested. A few questions that may steer your wind planning & climates: what's your axial tilt? Is it the 23 degrees you refer to as a break point? Does your world have enough orbital eccentricity to accentuate or mute the summer/winter effects from tilt? Are these the only landmasses?

    I have started a tutorial ( I need to apologize to Slipguard every time I mention it til I get it finished :-) ) on figuring wind and ocean currents. Some others here have written up how they figured things - in particular I recall seeing Naeddyr's amazing Ysi Earth II - that's the Featured Map page for it; follow the link to the WIP thread. It is an amazing stream-of-cartography lesson. Note that in the heat of battling climate issues, Naeddr swore off ever doing another such thoroughly rationalized climate map.... don't pay that too much heed.

    A significant issue in figuring rain shadow effects is that with an axial tilt, those nice generalized wind patterns are going to oscillate north-south between summer and winter. So really, the only "reliably shaded" area would be one where both summer and winter general winds go the same way. Or same-ish way... Too, you won't get neat bands, unless you have a cue ball of a planet (or a mostly gaseous one - see Jupiter's and Saturn's banding). Instead, you get general highs and lows, with attendant clockwise and counterclockwise flow (flipping once you cross the equator) (and here one means "heat equator", roughly the latitude at which the sun at noon is straight overhead) (BUT strongly modified N-S by large land and sea masses). Also, any such pattern is the general airflow. There'll be plenty of weather activity that differs from time to time.

    Got a used bookstore nearby? Grab a college climatology / weather textbook. A well-spent five to ten bucks. There's a wealth of info on the web too, but it helps to know the terms to search for. There's NOT many treatments of generalized arbitrary worlds - most understandably are Terra-centric.

    "Most tropical cyclones form on the side of the subtropical ridge closer to the equator, then move poleward past the ridge axis before recurving into the main belt of the Westerlies" ( Wikipedia ) . Here's a map of one of my worlds showing general cyclone tracks.
    Attachment 36923
    That planet has its own wiki (many people's work!) where I have a Cyclone distribution article that might give you ideas. A similar coverage of Earth's cyclones shows graphically the curving effects and where they spawn. You can see they just don't cross the equator.

    So that's Q3. Q2 I'd wait to figure til you work out likely (or just plausible - there ARE no climatology police here :-) ) summer/winter patterns. Q1 - yep, you could get rain dumped on the upwind side of a range, and some of the rainfall running "around the corner" across the resulting dryer area, or maybe through a pass in the range. Remember if there's much of a cleft in a barrier range, the wet air will seep through too, muting the rain shadow effect. Or a continent-spanning river (cf: Nile) could catch rain in a wet area and run across unrelated dry areas.

    Have you read Redrobes' river location tutorial? Ascension put a mini-tutorial in a post in a thread about where to place stuff. njordys put up a nice climate zone / rainfall map pair - you can infer the prevailing winds, but you need a January vs. July pair, which by the way shows what drives the ocean currents. Here's a prettier view - kind of the average of those seasonal prevailing winds. If you're used to thinking in terms of high and low pressures and what they do to weather, this pair are useful. The rules of thumb about what forms over a large-ish landmass or large-ish ocean in which season, will let you guess something like this for your world. Reason I asked if these were the only landmasses is that the behavior over an uninterrupted hemisphere-size ocean would lean more toward the ideal than our "continental high in winter" thought.

    Not complex enough? Well, those are the surface winds. Another big driver in climate & weather is the jet streams, as you can see in many weather maps. They're pretty dynamic, so maybe less use in predicting average patterns. But if you're using your world for anything other than a pretty map, knowing when and where the storms run could be hugely important. this site has jetstream maps down at the bottom - there's more golden info all up and down it too. Such as a clue why some latitudes have much more of wet season / dry season, than what we temperate-zone folks think of as summer and winter. Then once you get all that air and water moving, it transports the very heat that drove the motion in the first place. THe mundane example is the 'abnormal' warmness of the northeast Atlantic thanks to the Gulf Stream. Generalized, that becomes a world map showing where heat gets shoved around.

    Waldronate posted a couple of awesome links that go into more detail about the other factors driving currents, including deep-water ones.

    Yeah, the forum's image-attacher thingamwhoozit sometimes glitches. For me a link is fine, 'stead of a thumbnail.

    That's a decent progression of rain & wind, then currents & climate. Just be willing to iterate it a bit, as for instance the ocean currents influence the temperatures which goes back and affects the rainfall, etc. Or stop the thinking at any point you like and just MAP.... it's all your set of judgements, and the rare person who decides to nitpick your exact climate can feel free to redo it to suit himself :-). Me; I look forward to seeing your process in action, so do please keep us posted.

  3. #3

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    Quote Originally Posted by jbgibson View Post
    Hey, Porklet. I'm no climatologist, nor do I play one on TV. Nonetheless, like you, I'm interested. A few questions that may steer your wind planning & climates: what's your axial tilt? Is it the 23 degrees you refer to as a break point? Does your world have enough orbital eccentricity to accentuate or mute the summer/winter effects from tilt? Are these the only landmasses?

    I have started a tutorial ( I need to apologize to Slipguard every time I mention it til I get it finished :-) ) on figuring wind and ocean currents. Some others here have written up how they figured things - in particular I recall seeing Naeddyr's amazing Ysi Earth II - that's the Featured Map page for it; follow the link to the WIP thread. It is an amazing stream-of-cartography lesson. Note that in the heat of battling climate issues, Naeddr swore off ever doing another such thoroughly rationalized climate map.... don't pay that too much heed.

    A significant issue in figuring rain shadow effects is that with an axial tilt, those nice generalized wind patterns are going to oscillate north-south between summer and winter. So really, the only "reliably shaded" area would be one where both summer and winter general winds go the same way. Or same-ish way... Too, you won't get neat bands, unless you have a cue ball of a planet (or a mostly gaseous one - see Jupiter's and Saturn's banding). Instead, you get general highs and lows, with attendant clockwise and counterclockwise flow (flipping once you cross the equator) (and here one means "heat equator", roughly the latitude at which the sun at noon is straight overhead) (BUT strongly modified N-S by large land and sea masses). Also, any such pattern is the general airflow. There'll be plenty of weather activity that differs from time to time.

    Got a used bookstore nearby? Grab a college climatology / weather textbook. A well-spent five to ten bucks. There's a wealth of info on the web too, but it helps to know the terms to search for. There's NOT many treatments of generalized arbitrary worlds - most understandably are Terra-centric.

    "Most tropical cyclones form on the side of the subtropical ridge closer to the equator, then move poleward past the ridge axis before recurving into the main belt of the Westerlies" ( Wikipedia ) . Here's a map of one of my worlds showing general cyclone tracks.
    Attachment 36923
    That planet has its own wiki (many people's work!) where I have a Cyclone distribution article that might give you ideas. A similar coverage of Earth's cyclones shows graphically the curving effects and where they spawn. You can see they just don't cross the equator.

    So that's Q3. Q2 I'd wait to figure til you work out likely (or just plausible - there ARE no climatology police here :-) ) summer/winter patterns. Q1 - yep, you could get rain dumped on the upwind side of a range, and some of the rainfall running "around the corner" across the resulting dryer area, or maybe through a pass in the range. Remember if there's much of a cleft in a barrier range, the wet air will seep through too, muting the rain shadow effect. Or a continent-spanning river (cf: Nile) could catch rain in a wet area and run across unrelated dry areas.

    Have you read Redrobes' river location tutorial? Ascension put a mini-tutorial in a post in a thread about where to place stuff. njordys put up a nice climate zone / rainfall map pair - you can infer the prevailing winds, but you need a January vs. July pair, which by the way shows what drives the ocean currents. Here's a prettier view - kind of the average of those seasonal prevailing winds. If you're used to thinking in terms of high and low pressures and what they do to weather, this pair are useful. The rules of thumb about what forms over a large-ish landmass or large-ish ocean in which season, will let you guess something like this for your world. Reason I asked if these were the only landmasses is that the behavior over an uninterrupted hemisphere-size ocean would lean more toward the ideal than our "continental high in winter" thought.

    Not complex enough? Well, those are the surface winds. Another big driver in climate & weather is the jet streams, as you can see in many weather maps. They're pretty dynamic, so maybe less use in predicting average patterns. But if you're using your world for anything other than a pretty map, knowing when and where the storms run could be hugely important. this site has jetstream maps down at the bottom - there's more golden info all up and down it too. Such as a clue why some latitudes have much more of wet season / dry season, than what we temperate-zone folks think of as summer and winter. Then once you get all that air and water moving, it transports the very heat that drove the motion in the first place. THe mundane example is the 'abnormal' warmness of the northeast Atlantic thanks to the Gulf Stream. Generalized, that becomes a world map showing where heat gets shoved around.

    Waldronate posted a couple of awesome links that go into more detail about the other factors driving currents, including deep-water ones.

    Yeah, the forum's image-attacher thingamwhoozit sometimes glitches. For me a link is fine, 'stead of a thumbnail.

    That's a decent progression of rain & wind, then currents & climate. Just be willing to iterate it a bit, as for instance the ocean currents influence the temperatures which goes back and affects the rainfall, etc. Or stop the thinking at any point you like and just MAP.... it's all your set of judgements, and the rare person who decides to nitpick your exact climate can feel free to redo it to suit himself :-). Me; I look forward to seeing your process in action, so do please keep us posted.
    So much respond to. Thanks for the feedback. I'll take them in order.

    The axial tilt is identical to Earth's. I wanted to create a believable natural world. So I stole from nature. Everything is proportionally the same but halved. The world is 12,000 miles in diameter around the equator, etc. The 23rd parallel refers to the area furthest from the Equator where there is above average rainfall year round, for the most part. I got my information from this site, http://www.blueplanetbiomes.org/planet.htm, which broke down the different climates of the world. It didn't go into weather patterns, depressions, or even water currents. Except when referring to a specific climate that relied on, for example, westerly winds. In answer to your second question, it is the only known land mass. I want to leave it open, but it is the only land mass in this hemisphere.

    Nice work. I didn't realize the winds moved that way based on High and Low Pressure. I got the wind patterns from the free excerpt from "A Magical Society: Guide to Mapping" by Expeditious Retreat Press. It's simplistic, but it suits my purpose. I had no idea that the wind patterns oscillated between the Winter/Summer. I am going to have to study this plethora of information you have given me. I have downloaded the images you were using in your tutorial post along with the Desert/Rainfall pair you linked to.

    I had previously downloaded Redrobe's tutorial, and I am going to move onto rivers, lakes, and ocean currents following this stage. Actually, it occurs to me that ocean currents are probably integral to this stage. I am going to have to look into that as well.

    Oscillating air currents, high and low pressure areas, and jet streams; dear lord what I have I done?

    I am going to have to take all of this in over the next couple of days. I appreciate all of the links and info; especially your own hurricane charts. Thanks again for the info. Will post soon.
    "I run away, therefore I am." - Monty "the Python" Descartes

  4. #4

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    Bookmarking this thread for use later on!
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    Guild Novice Hawksguard's Avatar
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    Quote Originally Posted by Porklet View Post
    Everything is proportionally the same but halved. The world is 12,000 miles in diameter around the equator, etc.
    Sorry I don't have time to comment on the entirety of your post atm. Loos like JB has some awesome info for you. However, the statement above kind of flashed red when I read it. First off, I'm assuming you meant 12,000 miles in circumference around the equator, not diameter, since you said you were halving things. A planet with 1/2 the circumference of the Earth is going to have about *1/8* the volume of the Earth (and assuming it is proportional, about 1/8 the mass), which would give it physical characteristics much closer to Mars than Earth. If this is a naturally evolved planet, a lot of your breathable gasses aren't going to be gravitationally bound to your planet, and you're going to wind up with something tenuous at best. Of course, you could say that your smaller planet has a mass similar to Earth's, but then, all that extra metallic iron in your planet's mantle is going to wreak havoc with your magnetosphere, turning everyone's brain synapses into a fine paste. Your planet would also rotate somewhat more slowly since it doesn't need to go as far to get that 24 hour day, resulting in much decreased wind patterns, weather, and climate. Also, I'm not sure a lot of Earth climatology models would be comparable with a planet with that much decreased surface area.

    When I was designing my world, I hit a lot of walls as well when trying to keep it habitable and similar to Earth and yet, at the same time, throw some variety in there. I managed to acquire a lot of leeway in making it a world terraformed by a highly advanced culture (with remnants of their terraforming technology still in place and functioning), but every time you tweak something it has the potential of throwing a lot of other things out of balance. For example, by making a planet where life had never evolved naturally on its own, I inadvertently deprived my developing civilizations of the primary fuel source (fossil fuels) that got humans through the industrial revolution. Whoops.

    Check out this list of things needed to have a stable, habitable planet.
    Last edited by Hawksguard; 07-07-2011 at 12:23 AM.

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    Guild Expert jbgibson's Avatar
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    Ooooo, cool caveats, Hawksguard. Porklet, if you need things to be AS THOUGH the circumference were half that of Earth, how about if you leave it earth-sized, and make your people (and critters, and plants) twice the size? :-) I mean, that has its own problems, but at ~6ft tall humans aren't at the theoretical limit of bio structures, right? Time could be local, with twenty-four (or whatever desired) parts of whatever the rotation period needs to be.

    Or hmmmm..... core has more lead than iron (pick magnetically inert heavy-ish metal), atmosphere is denser than earth's, yadda, yadda. Or it outgases nitrogen and oxy at a rate that makes up for increased loss from somewhat lower grav..... there's AlWaYs rationalizations, even if they may not be proven rational, ifyaknowwhattImean.

    What have you done? Created parameters for a delightfully complex puzzle. If it gets to be a harder puzzle than you wanted, cheat. Or redefine success. :-)

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    Guild Expert Gracious Donor Hai-Etlik's Avatar
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    Quote Originally Posted by jbgibson View Post
    Or hmmmm..... core has more lead than iron (pick magnetically inert heavy-ish metal), atmosphere is denser than earth's, yadda, yadda. Or it outgases nitrogen and oxy at a rate that makes up for increased loss from somewhat lower grav..... there's AlWaYs rationalizations, even if they may not be proven rational, ifyaknowwhattImean.
    Iron is the heaviest thing that there's enough of as it's the heaviest product of stellar nucleosynthesis. Heavier elements require more energetic and rarer processes to form, like supernovae and particle accelerators.

  8. #8

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    Quote Originally Posted by Hawksguard View Post
    Sorry I don't have time to comment on the entirety of your post atm. Loos like JB has some awesome info for you. However, the statement above kind of flashed red when I read it. First off, I'm assuming you meant 12,000 miles in circumference around the equator, not diameter, since you said you were halving things. A planet with 1/2 the circumference of the Earth is going to have about *1/8* the volume of the Earth (and assuming it is proportional, about 1/8 the mass), which would give it physical characteristics much closer to Mars than Earth. If this is a naturally evolved planet, a lot of your breathable gasses aren't going to be gravitationally bound to your planet, and you're going to wind up with something tenuous at best. Of course, you could say that your smaller planet has a mass similar to Earth's, but then, all that extra metallic iron in your planet's mantle is going to wreak havoc with your magnetosphere, turning everyone's brain synapses into a fine paste. Your planet would also rotate somewhat more slowly since it doesn't need to go as far to get that 24 hour day, resulting in much decreased wind patterns, weather, and climate. Also, I'm not sure a lot of Earth climatology models would be comparable with a planet with that much decreased surface area.

    When I was designing my world, I hit a lot of walls as well when trying to keep it habitable and similar to Earth and yet, at the same time, throw some variety in there. I managed to acquire a lot of leeway in making it a world terraformed by a highly advanced culture (with remnants of their terraforming technology still in place and functioning), but every time you tweak something it has the potential of throwing a lot of other things out of balance. For example, by making a planet where life had never evolved naturally on its own, I inadvertently deprived my developing civilizations of the primary fuel source (fossil fuels) that got humans through the industrial revolution. Whoops.

    Check out this list of things needed to have a stable, habitable planet.
    I did mean circumference, but since it won't work as I envisioned I am not opposed to doubling the size. When I started this thing, o so many years ago, it was 1,000 miles by 1,500 miles, and it only included the mainland and few small islands. I've come this far, what's another 3,000 miles? The distance from the equator to either pole is roughly 6,000 miles, correct?

    I am working with a 3,000 x 3,000 pixel map that stretched from 75 degrees N to 15 degrees S (or 90 degrees). It was one mile per pixel, but at 2 miles per pixel the distance from the top of the map to the bottom following the same longitude should be 6,000 miles. Is that right?

    Since I stared recreating this world it has grown and changed a lot. I'm OK with a bit more.

    I am still reading thru the info JB provided, and I'm deciding how far I want to take this. The Summer/Winter wind patterns, upper ocean currents, hurricane activity, rainfall, regional climate, and curious or unusual weather patterns are pretty much the limit. I am looking into the H/L Pressure systems, jet stream, and deep ocean currents. I am redefining the Rain Shadows based on JB's new information. I will post tonight.

    EDIT: It might be childish, but I can't help but chuckle when I read the word panspermia in the article you referenced above. It happened again.
    Last edited by Porklet; 07-07-2011 at 07:30 PM.
    "I run away, therefore I am." - Monty "the Python" Descartes

  9. #9

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    Quote Originally Posted by jbgibson View Post
    Ooooo, cool caveats, Hawksguard. Porklet, if you need things to be AS THOUGH the circumference were half that of Earth, how about if you leave it earth-sized, and make your people (and critters, and plants) twice the size? :-) I mean, that has its own problems, but at ~6ft tall humans aren't at the theoretical limit of bio structures, right? Time could be local, with twenty-four (or whatever desired) parts of whatever the rotation period needs to be.

    Or hmmmm..... core has more lead than iron (pick magnetically inert heavy-ish metal), atmosphere is denser than earth's, yadda, yadda. Or it outgases nitrogen and oxy at a rate that makes up for increased loss from somewhat lower grav..... there's AlWaYs rationalizations, even if they may not be proven rational, ifyaknowwhattImean.

    What have you done? Created parameters for a delightfully complex puzzle. If it gets to be a harder puzzle than you wanted, cheat. Or redefine success. :-)
    I'm OK with a larger earth like planet. As I was designing the land masses (even at double the distances) I had found that over the course of 2,000 years (roughly) my cultures would become a lot more intermingled than I had originally anticipated. I don't mind that, but I want a majority of it to happen in story or game. With more land there's more elbow room, and "we got ta got ta git cha some elbow room," to quote Schoolhouse Rocks.

    I'm still looking over the vast amount of information you provided. Will post tonight.

    One question, when the wind patterns reverse themselves from winter to summer and back again (if I am understanding this correctly) I am sure they don't just wave at each other and start running back the way they came, right? Is there a gentle transition?
    "I run away, therefore I am." - Monty "the Python" Descartes

  10. #10

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    I am going to have to take this one step at a time. There's just too much information to digest all at once. I am starting with the wind.

    Using JB's Megalaos Summer pattern (reposted below for convenience) I applied it to my conical map. My map is also a Summer Map. I had to estimate the latitudes extending out from the center, because I didn't feel like drawing curved lines for the next two days. The red line is the "solar equator" at 23 degrees (measured). Again, I didn't extend it because it would have to curve. The Horse Latitude (normal 30) and the Subpolar Low (normal 60) are at 53 degrees and "off the map". I didn't know what changes that last part would make so I just went with it.

    The map is cluttered with wind arrows, and I just started plunking them down with only the basic framework of JB's pattern in mind. I wasn't sure how much effect mountains would have on the wind currents. The shifts due to mountain ranges might be exaggerated. I have not included Tradewind references, calms, or hurricane breeding grounds, yet. I have specific questions below:

    1. How much do mountains affect the wind currents? Can they alter their path? Does it differ based on elevation?
    2. Is there less wind effect over land? (I noticed on some of the real world wind maps circa 1901 provided by JB in his original post that there are a lot less arrows over dry land).
    3. What creates a Calm or Doldrum? I have noted their positions on maps of our earth, but I can't figure exactly why they occur.

    This is only a first draft, and it included all of my thoughts on the subject (thus the massive collection of arrows). I am going to clean it up, but I need to know if I'm on the right track. Once I get this completed I'll move on to the Winter Map, place Doldrums, etc. First things first, for the love of god help me!

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    P.S. I am a little disappointed no one got my "How To Make Friends and Influence People" reference in the thread title with a fart joke thrown in.
    "I run away, therefore I am." - Monty "the Python" Descartes

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