# How big of mountains?



## SeverinR (Oct 26, 2011)

I have a mountain range that divides woods from a scrub type desert(much like Arizona) not the sand dunes.

The team travels through the mountains, one day up and half day down.  In our world would this be tall enough to block moisture from the woods from getting to the desert?



> Many deserts are formed by rain shadows; mountains blocking the path of precipitation to the desert (on the lee side of the mountain).



The Rocky mountains does cause the rain shadowing, but they take time to travel through with wagons.
Can a narrow mountain range cause the effect, and still allow 1 day travel?

Dragon spent three days flying around the mountain because it was winter and she didn't want her baby exposed to freezing mountain air, if that helps.

Tucson Az is in a valley, this prevents alot of tornados, but they don't block much if any moisture.


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## mythique890 (Oct 27, 2011)

It doesn't sound to me like those mountains would be tall enough, but then anyone traveling through them wouldn't be walking up and down whole mountains, but taking passes.  The range sounds pretty narrow though, like it would have to be a single line of mountains instead of the several-mountains-thick ranges that are the only ones I've ever seen.  Of course, I live in the middle of the Rockies, and it would take several weeks to cross those on foot.


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## Ravana (Oct 27, 2011)

I'd say that unless it was a very low pass in an otherwise high range, that probably isn't going to do it. However, it depends on a lot of other things as well, not least of which being how high the terrain is in the first place. If you're already at 8,000 feet above sea level, it won't take much additional to interfere with moisture transfer. It also depends on how wet you want the forest to be and how dry you want the scrub to be. The difference doesn't necessarily have to be all that great. Also, if the location is far enough inland, a good chunk of the moisture will have already precipitated out; the ridgeline might just be peeling off the majority of what's left. 

The most extreme example of rain shadow I'm familiar with is the Atacama Desert in Chile: literally the driest places on Earth, separated from the Pacific Ocean by a single ridge. But a very _high_ ridge. Average rainfall throughout most of the region is one millimeter per year (no, that's _not_ mistyped); some weather stations in the desert have _never_ received rainfall… ever. (Though what's even more amazing is that things still manage to live there.) Obviously, this is more than you're wanting, but it could give you a good point of entry for further research. For a less radical–and probably more useful–example, you might look at the Iberian Peninsula (Spain and Portugal), which has large dry areas in the interior in spite of being surrounded by seas on three and a half sides.


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## SeverinR (Oct 31, 2011)

Sorry, forgot I posted this.

The woods are pretty dense, and the desert is Sonoran desert type.
Sonoran Desert - DesertUSA
Although not to far away it is sand dunes type desert.

Woods would be this type:
central California woods - Bing Images

Might have to increase ride time, week? two weeks in summer?
Fly around the mountain range would probably half of ride time. (To avoid freezing mountain temps with a new hatchling) 
Fly over would take a couple hours?

Starting editing, so now would be the time to correct this.


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## Elder the Dwarf (Oct 31, 2011)

Sierra Nevadas are one of the most extreme examples of a rain shadow I can think of.  There is a temperate rainforest on one side (I think its called the Hoh but I really don't know) and on the other side it is very dry.  Don't think there's a desert there though.  

And Ravana, if you've seen videos of the Atacama, it is pretty amazing.  The plants that live there survive off of dew from mist that comes off the ocean.  I think there's a part featuring the Atacama on Planet Earth.


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## Ravana (Nov 1, 2011)

Yep, saw that. It is amazing. Life is one _tough_ mother, ain't she? 

Though what it left me wondering was just how long it took those scientists to realize the desert was receiving the equivalent of a couple dozen inches of rainfall a year from nothing _but_ dew?


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## SeverinR (Nov 2, 2011)

So how long would it take to climb a rain shadow mountain in a two horse wagon, even with a fairly good pass through?
Days, weeks, months.
I think the rockies was weeks? 

To keep the dragon flying the long way around, the pass has to go up into a freezing climate and be more then several hours in the frost.


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## Ravana (Nov 5, 2011)

"Even with" a fairly good pass through? I can tell you how long a wagon would take to climb _without_ one.… 

Remember: the Rockies aren't a "range": they're a quarter of the bloody continent. Though, of course, most people traveling through them would aim for the parts that had large flat stretches mixed in, or where they weren't quite as wide. It doesn't take that much mountainage (yes, I just made that up) to block rain; all it takes is sufficient height relative to the prevailing winds in the area. If the prevailing winds paralleled them, rather than crossing them, the effect would be much easier to achieve (and would also cause more moisture to precipitate out on the wet side as they went along). 

Ultimately, travel time doesn't depend on how high the mountains are, so much as it does how low the pass is. Which can be ground-level, for all the difference that makes: very little rain is going to be able to squeeze through, if it's narrow enough. (It might be difficult to explain the existence of _quite_ that shallow a pass… but it doesn't have to be all that high.) The pass doesn't need to "rise into" freezing air, either: not as long as the freezing air is willing to come down far enough. The average elevation of the Great Plains is less than 500m above sea level; ask anyone who lives there how cold it gets in winter. In those conditions, your dragon may be obliged to take a somewhat lengthier detour even than you planned… say, via Acapulco.


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## SeverinR (Nov 8, 2011)

My other thread asking about severe updrafts, added a problem to this mix.

So now the desert side of the mountain drops lower then the wooded side, so there will be cliffs.  Making a nice snaking pass through the mountains and cliffs, that the military built a base near, that allowed dragons to live in their natural enviroment and still be able to cover wide areas. 
So I figure minimum 300-500 ft drop on desert side compared to wooded side.  Maybe even giving it a death valley type elevation.


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## Erica (Nov 25, 2011)

The coastal range of CA is probably a tad smaller than your world's mountains (you could probably ride across them on horseback in a day or two). They don't seem to cause rain shadow per say (when it rains on the coast it often rains inland though we do seem to be a bit drier in the Sacramento valley). However, they do cause a huge temperature difference. Our winters tend to be cooler and our summers a lot warmer than the coast. The Sierra cause a lot of rain shadow in Nevada, but those mountains would likely take more time to travel through than a couple of days with wagons/horses (think of the poor Donner Party). You might be able to invoke a narrow and low pass of sorts where your mountains are lower or much narrower than the rest of the range for some reason. It could allow fairly quick access in that one place, but still allow for the rain shadow effect along the eastern side of the range. My husband studied weather patterns in grad school, so I'll check with him and get back to you if he says something different.


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## SeverinR (Nov 25, 2011)

Erica said:


> The coastal range of CA is probably a tad smaller than your world's mountains (you could probably ride across them on horseback in a day or two). They don't seem to cause rain shadow per say (when it rains on the coast it often rains inland though we do seem to be a bit drier in the Sacramento valley). However, they do cause a huge temperature difference. Our winters tend to be cooler and our summers a lot warmer than the coast. The Sierra cause a lot of rain shadow in Nevada, but those mountains would likely take more time to travel through than a couple of days with wagons/horses (think of the poor Donner Party). You might be able to invoke a narrow and low pass of sorts where your mountains are lower or much narrower than the rest of the range for some reason. It could allow fairly quick access in that one place, but still allow for the rain shadow effect along the eastern side of the range. My husband studied weather patterns in grad school, so I'll check with him and get back to you if he says something different.



Thanks.
I have added a pass through the mountains. Still high enough to be too cold for the baby dragon(So the trip around would still be needed.) but fast enough to allow two-three day mountain trip.


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## demented-tiger (Nov 26, 2011)

Most rain shadow mountain ranges would probably take 3-5 days to cross - in the summer. In the winter, all the moisture they'd block would come down as snow. Travel would be severely limited, if not impossible. Early pioneers tried to cross the Rockies and the Sierra Nevada as early as they could to avoid getting trapped by the winter snows and avalanches. When the transcontinental railroad was built through the Sierra, they had to use special structures called snow-sheds to protect the tracks from getting buried by drifts. To this day, many roads through the mountains are seasonal, and close in the winter. You would need either some kind of structure to protect the road from snow drifts and avalanches, or a network of outposts/checkpoints/alpine villages with people to patrol the road and clear away the snow.

If there are none of these, then unless your characters can cross the mountains by sleigh (assuming horses can keep up thier endurance while bounding through deep, powdery snow), they'd be better off going the way of the Yukon travelers - dogsled, snow shoes, or skis. A wagon would get stuck in a drift, or slide on an icy patch into a ravine or a drift. Traveling on foot or by sled would take probably a week or so. In the thin mountain air, you'd need to stop to catch your breath. You couldn't exert yourself too hard, lest you started to sweat. Sweat makes a person colder, especially in the wind, and as temperatures drop below freezing, sweat becomes deadly.

If the pass was more like a gap, your idea might work. Ideally, a gap would be a narrow valley (probably a two or three miles wide) between the mountains where a river or some other feature passed through. It wouldn't have to be that high, probably 3000 or 6000 feet high (I'm going off of Arizona elevations: these are elevations that are mostly free of snow in the winter, or have thin patches of it; but where tempuratures drop close to or below freezing every night). Your characters could easily pass through this area in a day or two in a wagon, while encountering, at most, an inch or two of snow after a really bad storm. Your dragon could even pass through here too, as daytime tempuratures would be a bit crisp and chilly, but not freezing.

Then again, why can't your characters just follow the dragon around the mountains? Unless she's a really fast flier (I mean, can maintain speeds close to fifty sixty miles an hour), most rain shadow mountains stretch for hundreds of miles. The Sierra Nevada stretch from southern California to somewhere near the Oregon border, where they merge with the Cascade and Coastal Ranges. The Rockies extend from northern British Columbia, near Alaska, to New Mexico, somewhere between Albuquerque and Santa Fe. If your story takes place around the southern end of these mountains, then why aren't there roads that loop around the southern end of the mountains? Why bother fighting your way through the mountains, when you can just simply go around them? Certainly there are settlements and/or watering holes all around the base of the mountains.


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## SeverinR (Nov 28, 2011)

demented-tiger said:


> Most rain shadow mountain ranges would probably take 3-5 days to cross - in the summer. In the winter, all the moisture they'd block would come down as snow. Travel would be severely limited, if not impossible. Early pioneers tried to cross the Rockies and the Sierra Nevada as early as they could to avoid getting trapped by the winter snows and avalanches. When the transcontinental railroad was built through the Sierra, they had to use special structures called snow-sheds to protect the tracks from getting buried by drifts. To this day, many roads through the mountains are seasonal, and close in the winter. You would need either some kind of structure to protect the road from snow drifts and avalanches, or a network of outposts/checkpoints/alpine villages with people to patrol the road and clear away the snow.
> 
> If there are none of these, then unless your characters can cross the mountains by sleigh (assuming horses can keep up thier endurance while bounding through deep, powdery snow), they'd be better off going the way of the Yukon travelers - dogsled, snow shoes, or skis. A wagon would get stuck in a drift, or slide on an icy patch into a ravine or a drift. Traveling on foot or by sled would take probably a week or so. In the thin mountain air, you'd need to stop to catch your breath. You couldn't exert yourself too hard, lest you started to sweat. Sweat makes a person colder, especially in the wind, and as temperatures drop below freezing, sweat becomes deadly.
> 
> ...



The dragon flies around the south end to keep her new hatchling dragon from the cold mountain pass, three days around flying, two days (wagon) to travel through the pass on roads passing close to ledges and dangerous terrain, so even the pass is basically closed in the winter.  
I am going to increase travel time though, three days flying around the mountian versus two days through the pass just isn't enough.  Will probably double the time, a week to fly around the mountain and three to four days to travel through the pass.


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## demented-tiger (Nov 28, 2011)

Ideally, it would take a day to cross the type of pass you're describing, but 3-5 days to cross the mountain range as a whole - about the same amount of time you're giving your party. But that's in the summer. In the winter, it would take slightly longer, since you'd be battling snow drifts. Most crossings through mountains follow river valleys as far as they can go, and only when there is no place else to go but up and over the ridges do they follow a pass. Snow tends to collect into deep drifts in these valleys in winter. Of course, if you follow a really narrow mountain gorge, then you probably won't run into these sort of problems. Bottom line: if you've ever driven through a mountainous area, you'll get a good idea of the types of terrain you'll encounter going up and down a mountain pass. This might help inform you about travel times, terrain, and scale.


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## Erica (Dec 5, 2011)

Also think about the actual distances. A horse can walk about 2-4 miles an hour and can trot at about 8-10. If you are riding your horse all day, you'll likely be alternating walking and trotting (galloping is something they can't do for very long any more than we can run at our fastest clip for very long). Horses in long distance endurance races can go 100 miles or more in a day, but they are specially bred and trained for this, are not heavily burdened and are rested/cared for after the events. Typical horses would be unlikely to travel more than 50 miles in a day under ideal conditions, and 20-30 is more realistic if the terrain is hilly or they are carrying much of a load. In the winter, with snowdrifts, they would tire more rapidly and go much more slowly. You'd also have to logistical issue of carrying enough food for the horses in the winter, since they would not be able to forage for grass in deep snow. Sleighs really don't work well in snow with heavy drifts-usually they're used on roads where the snow is packed down.

So if the mountain pass is about 100 miles across and not too steep, then it could be crossed in about 3 days with decent horses that aren't overly burdened and if it's not muddy or snowy. I'd just make my mountains the width they need to be for the length of the journey you have in mind.

I'm afraid I'm not sure how fast dragons can fly, but I assume it's faster than a horse can walk/trot.


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## SeverinR (Dec 7, 2011)

Erica said:


> Also think about the actual distances. A horse can walk about 2-4 miles an hour and can trot at about 8-10. If you are riding your horse all day, you'll likely be alternating walking and trotting (galloping is something they can't do for very long any more than we can run at our fastest clip for very long). Horses in long distance endurance races can go 100 miles or more in a day, but they are specially bred and trained for this, are not heavily burdened and are rested/cared for after the events. Typical horses would be unlikely to travel more than 50 miles in a day under ideal conditions, and 20-30 is more realistic if the terrain is hilly or they are carrying much of a load. In the winter, with snowdrifts, they would tire more rapidly and go much more slowly. You'd also have to logistical issue of carrying enough food for the horses in the winter, since they would not be able to forage for grass in deep snow. Sleighs really don't work well in snow with heavy drifts-usually they're used on roads where the snow is packed down.
> 
> So if the mountain pass is about 100 miles across and not too steep, then it could be crossed in about 3 days with decent horses that aren't overly burdened and if it's not muddy or snowy. I'd just make my mountains the width they need to be for the length of the journey you have in mind.
> 
> I'm afraid I'm not sure how fast dragons can fly, but I assume it's faster than a horse can walk/trot.



I have not considered how fast a dragon could fly, they are huge armored beasts so they won't break speed records.  Maybe 30 miles per hour pushing it? (3 times horse trot) and speed dragons would be close to 50mph(smaller, bigger wings, and thinner skin(ie not armored)

My first thought when refering to horse travel: Alternating between walk and trot, was in trail rides I never trotted, but then I realized I did, to catch up when lagging behind.  Also horses stop for water and human needs subtract from a continous walk.


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## Steerpike (Dec 7, 2011)

SeverinR said:


> I have not considered how fast a dragon could fly, they are huge armored beasts so they won't break speed records.



I think when one interprets them as magical creatures there can be quite a bit of leeway here. If you're really looking at them anatomically and trying to figure out how fast they go, you have to first start with the realization that most dragons as depicted in fantasy works probably wouldn't be able to fly at all if you judged them solely from mundane and anatomical viewpoints.


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## Ravana (Dec 8, 2011)

Steerpike said:


> If you're really looking at them anatomically and trying to figure out how fast they go, you have to first start with the realization that most dragons as depicted in fantasy works probably wouldn't be able to fly at all if you judged them solely from mundane and anatomical viewpoints.



Not even close to able to fly, in fact. The critical wing loading ratio for birds is somewhere between 20 and 25 kg per square meter of wing… and a square meter is a _lot_ of wing–as witnessed by the fact that the heaviest bird species that _can_ fly normally top out around 16-18 kilos. (The record even for these species stands at a mere 21 kilos; no mention of whether or how well it flew… presumably "not well enough," since it got measured.  ) 

The problem is that weight is a function of volume, whereas wing surface is one of area, so doubling the girth of a creature's torso–for simplicity of calculation, consider this a cylinder–means roughly a twelvefold increase in weight, requiring an equivalent increase in wing area… oh, call it six times as wide and twice as deep, though other ratios are possible. (Length is simpler: double the length, double the weight. Of course, if you're doubling both length and girth, then the weight has gone up 24 times.…)

(Actually, the volume calculation falls somewhere between that and a pair of cones: a good approximation could probably be achieved by dividing the length into three parts, treating the center as a cylinder and the ends as cones, though at that point you need to start taking into account a host of other factors, such as whether this should be three equal parts–probably not–the taper of the cones, etc. Anybody who wants to do this on their own, go right ahead. Even a rough guesstimate tells me you'll get a minimum 8x volume increase for doubling of girth at the center.)

Now… how big do you want your dragons to be? Large enough for a human to ride? Torso's going to be at least as big around as a horse, and probably at least three times as long (you need to have room to attach the wings, remember!); even with lower bone mass, you're still looking at close to three times a horse's weight… before throwing in legs, neck, tail, and the wings themselves. Worse, bones are light compared to muscle to begin with–and your dragon's going to need plenty of muscle to work those wings, even if nearly all its flight time involves gliding; worse still, you probably aren't going to be able to reduce bone mass in the first place, since heavier muscles require heavier bones. A good mid-size riding horse comes in at around 450 kg, so you're looking at 1300+ kg or so of dragon, minimum. At the same wing load limit as birds, that means a minimum wing area of 65 square meters… or wings close to 11 meters long (each!) and 3 meters deep. (Why not deeper? Because we're discussing an overall length three times that of a horse–and horses are not three meters long, so even that's being generous.)

And that's before adding the weight of the rider. Another 70-80 kilos, give or take, requiring another 4m wing area. And that's also ignoring the difference in weight between feathers and "leathery" wings.

Of course, most fantasy dragons are _considerably_ larger than this.… So, no, they couldn't fly, without some magical assistance.

Speed is actually easier to answer, at least in part: they'll be able to get within a few percentage points of the wind they're using… as long as it's behind them. Depending on their oxygen and temperature requirements, this could be very fast indeed. In fact, they could exceed the speed of the wind by angling themselves correctly–the record for a sailboat is 1.71x wind speed, and iceboats can manage 5x wind speed or more. On the other hand, neither of these needs to worry about pesky little things like gravity hauling them down to a surface, since they're already on one, so they can heel over at almost any angle they like to maximize their advantage; a flying creature is going to start losing lift rapidly once it passes more than a few degrees off level. 

If the wind _isn't_ blowing in a favorable direction, on the other hand, they might be fortunate to make headway at all. And the only way to drive those wings harder is going to be more muscle; you can imagine how rapidly this leads toward diminishing returns. So basically how fast the dragon can travel will depend on what kind of winds you decide to bless it with in your story, 'cause it ain't gonna get very far by flapping.


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## arbiter117 (Dec 9, 2011)

COnsidering you are talking about an area much like where I live, I will tell you it sounds practical enough. The mountains of SoCal can be walked over (i imagine, in some parts) within a couple days (I've never tried this, but it seems possible enough) The tallest mountain in SoCal (near where I live) is San Gorgonio, its about 11,000 feet high and takes most of a day to climb up (i doubt in real life if someone would climb to the top of a mountain, they would probably take a less steep and much flatter route like a mountain pass)

Anyway, on the other side of said mountains in the lovely shrubby desert of Palm Springs and friends. So what you are asking for may not be a 1 day up and half down, but im sure it wont be more than 2-3 tops. I hope this helps.


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## SeverinR (Dec 19, 2011)

arbiter117 said:


> (i doubt in real life if someone would climb to the top of a mountain, they would probably take a less steep and much flatter route like a mountain pass)
> .



The human mind is strange, someone looks at a mountain and decides to climb it, even if there is an easier way around.

But thanks it does help.


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