Fog eaves

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A conifer ( Abies lasiocarpa ) with dew pearls , which apart from their origin are identical to the fog eaves

As fog eaves or Nebeltau is referred to from a mist settling on surfaces, liquid precipitation . Fog eaves only occur when the fog has sufficiently large droplet sizes and is consequently oozing . The air temperatures must also be above the freezing point of the water , i.e. 0 ° C, as otherwise frost or ice will form.

Fog eaves fog up on all surfaces that come into contact with it, which can take on larger dimensions, especially in the case of coniferous plants . The high specific surface area of the needles or any other suitable surface extract part of its water from the fog, which reaches the ground via various routes and thus contributes to the amount of precipitation . The Canary Island pine is to be withdrawn because of their strong tufted needles able to damp trade winds two to three times the normal precipitation.


Fog eaves play an important role as a water source, especially for plants in regions with high or, above all, regular fog occurrence and otherwise little water supply. This particularly affects vegetation on mountain slopes near the coast of tropical and subtropical areas with wind or temperature conditions that do not allow rain. One therefore speaks of cloud forests . In the case of Central European flora, on the other hand, the hydrological influence of the fog eaves is comparatively small, here the pollutants dissolved in the fog droplets play a role.

The very regular fog in otherwise arid areas can also make an important contribution to the drinking water supply for humans , and to a limited extent even to the service water supply. This is being researched in stations such as Gobabeb and successfully applied in test facilities on the South Pacific Andean slopes. Since the artificial fog eaves can be erected and maintained very inexpensively with the help of a few fine-meshed nets, it is particularly suitable for developing countries.


The fog eaves are usually measured indirectly via a fog catcher , i.e. a fine wire mesh over a rain gauge that simulates the fog obstacle. A direct measurement of the stem or stem runoff is possible using funnels that are attached to the desired runoff area. The droplets of the captured fog water can be easily collected.