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 Informations
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| | » Mines ! | | |
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| | You have to be very carreful before to go to trek in Bosnia, the country was in war from 1992 until 1995, and a lot of areas are still heavily mined, it will be completely stupid and dangerous to go to trek without any information about mines in the aera where you are going. | | |
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| | » Security before to go | | |
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| | Before to go to trek, you always have to take care about the following points :
- Be aware about mine risk !
- Try to never go alone, especially during winter, you never know what can happen in mountain.
- Always let know somebody where you are going.
- Check carefully the weather forecast.
- Always watch the time and be sure you are still in your timeline, think after reaching the summit you still need time to coma back before night.
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| | » Checklist in order to prepare a trekking | | |
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| | - Water (between 2 and 3 liters depending of season), and food.
- Sun glasses.
- Map and compas (compas can save your life during difficult condition).
- Solar cream.
- Hot clothes during winter, cover every part of your body, winter wind in moutain can be very dangerous.
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Mountains weather
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The foehn effect
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| The foehn is generally a wind from south, it take place in some good oriented axes moutain-valley. When a wind cross a mountain, air is increasing in order to pass above, this movement make the air more cold (by dry air, this air loose 1°C by 100m, 0.5°C if air is humid). Depending of how the air pass above the moutain and how humid is the air, a cloud can appear in the windy side of the mountain. |
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if the wind/humidy are strong, and the mountain good oriented, the foehn can become important and it can be raining (or snowing) in the windy side. In the other side, air is dry, without cloud and air is abnormally hot : reason is the air is winning 1°/100m when descreasing (because dry air), and win only 0.5°/100m when increasing (because humid air). |
| For example, if temperature is about 10° before the air increase to pass above a moutain of 1000m, it will be about 5° at the top of the moutain (10-10*0.5), and 15° in the other foot of the moutain (5+10*1). |
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Local mountain wind
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Local wind (increasing)
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| The sun warms the mountain slopes, increasing the temperature of air in contact with the ground. This air is becoming less heavy than air at same altitud, starting to increase, the air come from the valley in order to renew it. |
By this principle, a wind goind from close valleys until summits is created. generally, this local wind appears in the middle of morning until the end of afternoon. It can reach 15-20 km/h in summer during sunny days and is almost not perceptible during winter.
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Local wind (decreasing)
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| During clear nights, the slopes radiate energy gained from the sun during the day into space. At the contact of floor, the air is becoming more cold, so more heavy, creating a wind going from summits to valleys. |
This local wind is generally very slow and almost not perceptible. It happens at the beginning of the night until the beginning of morning.
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Temperature
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Ascent and descent of air
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 The forced ascent of air creates a cooling of 1°C/100m with dry air, around 0.5°C with satured air.
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Mountain wind and its consequences
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Wind curves
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When a general wind movement approaches a moutain, his behavior will depend of the mountain form.
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A moutain alone will not curve too much the wind line, because wind can pass by the side, but in the case of a moutains range, the wind have to pass above. |
To pass above a moutain, the wind have to increase. This movement create a pressure close to the summit, so the wind speed is increasing. This case is called "Venturi effect". It's possible to find the same kind of principle in a valley, when the wind has just a little place to pass, like a tunnel effect. |
| One of the biggest danger of the wind in moutain, is the temperature felt by the body : more the wind speed is important or the temperature low, more the temperature felt is low. The following schema give an idea bout the temperature felt : |
| Speed of wind (km/h) | 10°C | 5°C | 0°C | -5°C | -10°C | -15°C | -20°C | -25°C | -30°C |
| 0 | 10 | 5 | 0 | -5 | -10 | -15 | -20 | -25 | -30 |
| 10 | 8 | 2 | -3 | -8 | -14 | -19 | -25 | -30 | -36 |
| 20 | 3 | -3 | -9 | -16 | -22 | -29 | -35 | -42 | -48 |
| 30 | 0 | -6 | -13 | -20 | -28 | -34 | -41 | -48 | -55 |
| 40 | -1 | -8 | -16 | -23 | -31 | -38 | -45 | -53 | -60 |
| 50 | -2 | -10 | -17 | -25 | -33 | -41 | -48 | -56 | -64 |
| 60 | -3 | -11 | -19 | -27 | -34 | -42 | -50 | -58 | -66 |
| 70 | -4 | -12 | -19 | -28 | -35 | -43 | -51 | -59 | -67 |
| 80 | -4 | -12 | -20 | -28 | -36 | -44 | -52 | -60 | -68 |
| Danger low |
| Danger increasing |
| Danger important |
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