You start for a hike in the mountains on a sunny day. And suddenly you become soaked. Yes it is a fact. We experienced it in Giona Mountain on August 15th. Sun and heat in the morning, hail in the afternoon. The weather in the mountains is changing very fast, especially now in the summer, and here are some tips that will help you to predict this changes. Don’t forget before you start to see the meteorological sites in order to have an idea of what awaits you. We are using www.mountain-forecast.com, www.windy.com and http://poseidon.hcmr.gr/which are quite accurate in their predictions.
Weather‘s Mechanism in the mountains.
During the day the air in the plains heats up faster than the air in the mountains. The wind that forms from the plains to the peaks of the mountains is called ascending wind. Respectively, when the cold air comes from the mountains peaks, it descends to lower altitudes and the wind that is created is called descending wind. This is the mechanism that creates the changing weather in the mountains. Especially for the mountains that are near the sea (eg Athos Mountain). The reason is Physics. Hot air masses rise rapidly, cool very quickly, and create storms and dangerous weather.
Forecast with Altimeter
The altimeter is an instrument that shows the altitude and its operation is based on the change of atmospheric pressure. Staying at a constant height (eg during long stops in our course) we check the indicator of the altimeter. If after a while and while we are in the same place, the altimeter shows a higher altitude then, bad weather is coming. If it stays the same or goes down then, we will have sunny and pleasant weather. The greater the changes in the indications, the more intense the weather will be. This is the technique that is used by modern mountaineering watches that predict the weather.
Look to the West
In the Northern Hemisphere the weather travels from West to East. That is why our observations are always made by looking at the West. In the Southern Hemisphere, observations must be made in reverse.
Observe the clouds
The clouds and their direction can say a lot about the coming weather.
CumulusNimbus are massive, dense dark clouds that grow vertically. If they are present in the morning in the sky and gradually increase, depending on the rate of the increase, dangerous weather and storms will come. If the wind is strong, blowing from the clouds towards you, then you do not have much time. Cirrus are white feather-shaped clouds. AltoCumulus are clouds shaped like cotton balls. They are usually formed on the peripherals of a distant bad weather system. If you see them in the sky, there is a possibility of bad weather in the next 36 hours.
The dense vertical clouds, narrower than the CumulusNimbus, with a shape like an explosion in the sky, are called Cumulus and show possible rain in the next 24 hours.
NimboStratus, are the low gray clouds that cover the sky over a large area, hide the sun or moon and bring rain.
Observe the sky
When the sky during the sunset is red then the weather will be good. When the sky is red during the sunrise, then the good weather has passed and since the weather travels from the West, a low weather system will follow. If you see a rainbow in the morning in the West, it means that humidity and rain are coming your way.
Observe the moon and the sun
A “ring” around the moon (otherwise in meteorology), is created by the reflection of light on the ice crystals. This usually means that the plaid will be damaged within the next 3 days
Flora and fauna the nature’s barometer
The behavior of insects and animals can show the tendency of the weather even in the very near future. Spiders make their webs sparsely and travel with it. The bees fly away from the hives. The bats fly in the afternoon. All this are indications that the weather will be good. If there are many insects that fly low and sting, the spiders make small and dense webs low in the trees and the bees disappear then the weather will soon get worse. Also in the mountain pastures, if the cows lie down and do not graze, a storm is coming. If there is dew on the plants before midnight or in the morning, then there will be no rain. If there is no dew on the plants at night for two to three days, there will be rain the next day.
And two tips more:
How close is the storm? When you see a lightning, start counting the seconds until you hear the roar. Multiply by 340 which is the speed of sound per second and voila. If you see the lightning and hear the sound after 10 seconds, then the storm is about 3.5km away (340 x 10 = 3400)
What is the ambient temperature? The higher the temperature, the more a cricket sings. At night listen to its song. Count how many chirps it makes in 14 seconds, add 10 and divide by 2. If for example it makes 30 chirps, then the temperature is about 20 degrees Celsius (30 +10 = 40/2 = 20), Take two or three more measurements and use the average to determine the temperature. A little bit complicated but it worth it.