"Visibility in the desert / steppe" Topic

A simple question (maybe…) what is maximum visibility distance (in meters, if possible) in a desert / steppe environment (= minimal terrain cover), at sight / with simple optical devices (WW1 / WW2 / 1950's)for:

a) infantry / support weapons
b) artillery
c) vehicles
d) field defences

thank you in advance

Here in Arizona you can see for miles (10-20 or more) except, of course, under the most extreme weather conditions. In short, you can see far beyond what you could hit with the direct fire weapons of the periods you describe.

From my yard, I can clearly see people hiking on a mountain two to three miles away with 8x35 binoculars. With bigger binoculars I'd be able to make out even more detail, further away.

It's the dry air. You don't get that haze you get in temperate climates.

In the desert seeing and identifying can be very different.

Numerous instances of mistaken identity ocurred well within viewing distances in the western desert because dust and haze make CLEAR vision very difficult.

If the viewer is not moving nor near any moving troops then the visibility is better but any moving force may be shrouded in dust which can linger long after they have moved away.

Are you asking for visibility or range? Visibility to the horizon depends on the height of the observer, the rule of thumb on the ocean is: 1.17 times the square root of your height of eye (in feet) = Distance to the horizon in nautical miles.

So if, for example, you are peering out of a tank turret 9 feet above the surface, the horizon that you see is about 3.5 nautical miles away. To see another object with height, you add the two distances. So you could theoreticaly see another tank 9 ft high 7 miles away.

This is theoretical maximum visibility difference, but of course not range.

I think the question is too vague here.

The theoretical maximum visibility is given by the curvature of the earth, as mentioned by tuscaloosa.

The actual visibility would depend on the weather (humidity, heat, wind blowing up dust etc.) and lighting conditions.

The chances of seeing an actual target would depend on the target type and whether that target wants to be seen or not – it would be easier to spot somebody standing in neon-orange clothes than another one taking cover in khaki clothes.

Griefbringer

Come take a vacation in the desert. We'll do some visibility exercises.

Allen

In the case of desert it very much depends on the time of day and weather conditions. In the mornings there is a 'mist' between land and horizon. During the day there is the heat haze.

Dust kicked up by vehicles could be seen at about 5 miles. Vehicles could be seen at about a 4000 yds (as dots) – again depending on circumstances. The trick was to get above the 'haze', as little as 20 feet could do it. You could generally identify a vehicle at 1500 yds.

Forget about devices – it only takes one man with binoculars to direct fire: "Fire at the dust!". You seem to think that everyone is a sniper – most soldiers just shoot in the direction of the enemy – seen or not – that's why casualties are so low and a lot of soldiers come home having fired hundreds (sometimes thousands) of rounds and never actually seen the enemy in person! (see MG's in most wars).

And don't forget that, in terms of line of sight, even steppes, desert and plains are very rarely flat. Take a look at a topo map for a desert and you can see that despite the lack of cover in terms of trees and hills, there are plenty of smaller depressions, wadis and so on.

In Mesopotamia artillery observation towers were constructed to increase spotting distances – not that it helped much with heat haze, dust and fog.

Are you asking for the distances these types of targets can be located in the open?

Infantry, 1000m if you are lucky. If they are stationary and deployed, much, much closer. I've missed someone in camouflage sitting on an earth bank 10m away.

Artillery pieces and vehicles are similar in size, anything up to 5km if moving, much harder if stationary. Dug in AT guns treat as infantry.

Slit trenches, bunkers etc should be almost invisible from the ground, obviously if the troops leave great heaps of spoil all over the place… Great big things like lines of dragons teeth or 100m deep wire entanglements are fairly easy to see. Advertising your defensive positions with easy to spot fieldworks is not usually adviseable.

I'd agree with most of what people said – all summed up, it depends on a lot of things and there isn't a set answer to your question. Haze, dust, time of day, target your trying to see – all come into play when trying to answer this.

I know it's not the answer you're looking for, but unfortunately that's reality for you – often hard to nail down exactly and often changing.

" Haze, dust, time of day, target your trying to see – all come into play when trying to answer this. … but unfortunately that's reality for you – often hard to nail down exactly and often changing."

Sounds like a good candidate for a die roll then.

Hi Mike,

yes, but one roll at 'dawn', one at 'day' and one at 'evening' when everything changed again; and it would be the same for everyone unless you go for who is looking east-west. On the note that nothing is dead flat, in the "Western Desert" I'm afraid that it pretty much is – miles and miles of it. It is mainly the slightly descending scarp slope of the Med' and that is why armoured forces were essential – infantry, on their own, generally got cut to pieces! A piece of ground 20 foot higher than the mean was a "strategic asset". I have viewed many a battlefields where a contour puts units on a 'hill' but when you get there the ground looks dead flat with no advantage for either, but apparently in the desert this was not the case because of the heat haze spoken of before.

Griefbringer

''The theoretical maximum visibility is given by the curvature of the earth, as mentioned by tuscaloosa.''

Not at all: you can see over the horison, even without light bending, as your target will commonly be above ground. If you include light bending, as it will with ground heat in certain atmospheric conditions (or ''diffracted'' if you adhear to the pre-Feynman term) then the theoretical viewable distance is infinate, limited only by the scattering effect of dust in the atmosphere.

The distance for a standing man to see another standing man on the horison (without light bending and in clear conditions) is 6.5 miles, assuming your eyes and the targets head are 6ft high. Your distance to a point on the ground at the viewable horison is half that.
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The calculation, is:

Height of viewer (in feet) x 7, divided by 4. Square root of result.
Add this to:
Height of target (in feet) x 7, divided by 4. Square root of result.

Total is the distance in miles at which you can see your target.

If you or the target is higher, or the target larger, then the distance becomes exponentially greater, especially if conditions allow light bending over the horison.
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So, if I was going to make rules based upon how far observers could see in a flat desert, then I would base them upon these factors:

Subject (either viewer or target):

Man prone:…………………………..1.3 miles
3ft high field defences/small artly:….. 2.3 miles
Man standing(or crouching with periscope)/larger artillery:
……………………………………3.2 miles
Man sat in lorry/lorry………………..3.7 miles
Tank turret, man standing on a lorry seat or man on artillery platform:
……………………………………3.9 miles
Man standing on top of lorry or tank:…. 4.5 miles

To find how far someone should see, then add the factor for the viewer to the factor for the target. Whatever you might think about these factors, they do at least give some base-line idea. You then need modifiers:

Three types of modifiers:

1) Fixed modifiers that will remain relatively stable for the game

Eg dust in atmosphere, waning light, fog etc can have the effect of reducing the visible distances for a fixed amount, so you could, for example, knock off 1 mile or half a mile from all distances. Or perhaps even to alter this distance after half way through the game as the sun goes down.

2) Positive modifiers

Heat. This really does increase effects uncontrollably, sometimes over hundreds of miles. If you include mirages (meaning the ability to view objects below the horison) and an effect called 'looming' then your visible distance is infinate. If it's very hot, then roll D6 dice and multiply the distance by half the result.

3) Mixed modifier

The Sun. This affects visibily in a certain direction. You can see further if the target is silhouetted against a bright background, such as the dawning or setting sun, or (just after sunset) a bright twilit sky or dawn sky. If the battle is in twilight, then the easiest would be to use something like this example: for viewing directly west multiply the viewible distance by half the dice roll and for viewing in the opposite direction decrease it by half the dice roll.

Hope this gives some ideas.

Heat shimmer really messes things up. Sure, you can tell there's a vehicle over there, but you can't tell how far away, or even what kind it is. And you can forget aiming at something that far away. Getting up high reduces the shimmer effect somewhat, but you're still going to get it over long distances.

Other problems might be a mist haze at night/morning, and windblown sand. If there are sand dunes, then all bets are off.. you won't know what's on the next dune over, much less three miles away. Sand and dust plumes will show up nicely, however.

At Fort Irwin (mohave desert) we could see vehicles kilometers away if they were moving and infantry out to about one kilometer. We would engage them even if we couldn't hit them so they would deploy and begin to fire and maneuver. By the time infantry reached us they were fatigued from conducting three to five second rushes.