Fog, dew and horizontal precipitation

Fog, dew and horizontal precipitation

Hidden water of mountain ridges and upper catchments

Water enters mountain ecosystems not only in the form of rain and snow. On ridges, coastal ranges, cloudy slopes, and in high-altitude zones, the following can play a significant role:

fog;

low clouds;

dew;

frost;

frost;

drip precipitation of moisture on vegetation;

condensation on stones and artificial surfaces;

small drops carried by the wind.

These forms of moisture are calledhorizontal precipitation, because the water does not come primarily from above, like ordinary rain, but is carried by air flow through vegetation, terrain, or special catchment structures.

The main principle:

The mountain ridge must not only receive rain, but also extract water directly from the moist air.

In areas with frequent fog, horizontal precipitation can support plants and soil even when rainfall is minimal. However, it cannot be considered a guaranteed or constant source of water. Its effectiveness depends on the season, wind direction, cloud height, droplet size, temperature, topography, and vegetation conditions.

1. The main forms of atmospheric moisture

1.1. Fog

Fog is an accumulation of small water droplets in the ground layer of air.

In the mountains it occurs when:

moist air rises up the slope and cools;

clouds touch the ridge;

cold air fills the valley;

warm, moist air passes over a cold surface;

nighttime radiative cooling occurs;

Sea air enters the coastal ridge.

Fog itself doesn't necessarily leave a significant volume of water on the ground. For this to happen, droplets must hit the surface and settle.

Such surfaces become:

pine;

leaves;

branches;

grass;

mosses;

lichens;

stones;

mesh mist eliminators.

1.2 Cloud precipitation

On high ridges, the cloud can pass directly through the vegetation cover.

The drops collide with the crowns and branches, combine and then:

drip onto the soil;

flow down the trunks;

wet the bark;

absorbed by mosses;

are retained in plant litter.

This influx of water is sometimes called cloud or fog interception.

It is especially important for:

cloud forests;

coastal mountains;

island ridges;

high-mountain shrub zones;

ridges regularly located at the lower boundary of the clouds.

1.3. Dew

Dew forms when a surface cools below its dew point at night and water vapor condenses on it.

Dew is most often formed:

on clear nights;

in light or moderate wind;

on open surfaces;

on plants with good radiative cooling;

in the depressions;

near humid air masses.

The volume of dew is usually much less than the volume of heavy rain, but its value lies in its regularity.

Dew is capable of:

support mosses and lichens;

moisten the top layer of the litter;

reduce morning water stress of plants;

provide moisture to insects;

support the germination of individual species;

reduce the rate of soil drying.

1.4. Frost and hoarfrost

At sub-zero temperatures, atmospheric moisture precipitates in the form of ice.

Frost

It forms mainly on cooled surfaces when water vapor turns into ice.

Hoarfrost

Occurs when supercooled fog droplets freeze upon impact with plants, rocks or structures.

After warming, this water enters the soil.

But heavy frost creates a load:

on the branch;

mist eliminators;

communication lines;

sensors;

fencing;

young trees.

Therefore, winter fog capture must be calculated together with ice and wind loads.

2. Why are combs especially important?

Mountain ridges are the first to encounter humid air masses.

When air rises on a slope:

the pressure decreases;

the air expands;

the temperature drops;

relative humidity increases;

water vapor condenses;

clouds and fog are formed.

If the ridge is at the height of the cloud base, it can regularly become immersed in fog, even when the valleys remain dry.

Particularly promising are:

coastal ridges;

island mountains;

windward slopes;

saddles through which moist air passes;

ridges near the ocean and large bodies of water;

transition zones between maritime and continental climates.

At the same time, neighboring peaks can receive completely different volumes of foggy moisture.

3. Horizontal transfer of water across a watershed

Moisture in fog is carried by the wind.

This means that water can:

form over the sea;

move in an air mass;

climb up the windward slope;

settle on the ridge;

flow into another pool.

Therefore, horizontal precipitation can create atmospheric water transfer between territories.

For the DREVO project this is especially important when connecting:

coastal zones;

mountain catchments;

upper forests;

springs;

internal arid slopes.

In some conditions, the ridge becomes not only a watershed, but alsoatmospheric water collector.

4. Foggy mountain profile

For each ridge, it is necessary to determine the vertical position of the fog belt.

He can:

stay at the same height all the time;

get up during the day;

descend at night;

change with the seasons;

disappear in dry years;

shift with climate change.

Conventionally, the mountain is divided into zones.

Zone below the fog belt

The air is humid, but vegetation is rarely immersed in cloud.

What's more important here is the dew and the water flowing down from above.

Lower boundary of fog

Brief contact with clouds.

Suitable area for mixed moisture collection systems.

Active fog belt

Most frequent cloud passage and maximum droplet interception potential.

Cloud top

Strong sun, variable fog and high wind load.

Zone above the clouds

There may be less fog despite the high altitude.

Therefore, installing mist eliminators simply “as high as possible” is wrong.

5. Natural fog eliminators

5.1. Conifers

Pine needles intercept small drops well thanks to:

large total area;

fine structure;

constant presence of foliage;

a multitude of droplet collision points.

However, dense coniferous stands can:

increase the fire risk;

create a heavy snow load;

lose some water through evaporation from the crown;

form a homogeneous vulnerable system.

5.2. Small-leaved shrubs

Shrubs with small leaves and dense branching:

intercept fog well;

more resistant to wind than tall trees;

create drip flow to the roots;

form wet islands;

protect the soil from drying out.

For open ridges they are often more practical than tall trees.

5.3. Plants with pubescent leaves

The hairs on the leaves increase the roughness of the surface and help to retain small droplets.

Such plants can be collected:

fog;

dew;

aerosol moisture.

However, strong constant moisture can increase the risk of fungal diseases.

5.4. Mosses

Mosses:

absorb water quickly;

hold it between the leaves;

slowly release moisture;

protect the soil;

maintain the microclimate.

They are especially useful:

on the stones;

near the roots;

on the northern slopes;

in the misty forests;

near the springs;

in protected wet pockets.

5.5. Lichens

Lichens are able to absorb atmospheric moisture directly through the surface of their bodies.

They:

use fog and dew;

withstand periods of drying out;

protect stone surfaces;

participate in initial soil formation.

Destruction of the lichen cover on an exposed ridge can dramatically reduce the surface's ability to retain fine atmospheric moisture.

5.6. Rough bark and dead wood

Bark and attached woody debris:

intercept drops;

direct water downwards;

create humid microzones;

support mushrooms and mosses;

reduce evaporation from the litter.

However, unsecured timber should not be placed in hazardous waterways.

6. The path of water through a plant

After the droplets settle, water can move in several ways.

Drip runoff from the crown

The drops combine and fall to the ground.

Flowing down the trunk

Water moves through the branches and trunk to the base of the plant.

This creates concentrated moisture near the roots.

Surface retention

Some of the water remains on the leaves, moss and bark.

Evaporation back into the atmosphere

Not all intercepted water reaches the soil.

If fog is quickly followed by sun and dry wind, a significant portion of the moisture may evaporate.

Therefore, it is necessary to distinguish:

general fog interception;

actual water supply to the soil;

beneficial replenishment of soil moisture.

7. Artificial fog eliminators

The mist eliminator is a semi-permeable mesh surface through which moist air passes.

Drops:

collide with fibers;

unite;

are increasing;

flow down;

fall into the gutter;

are directed to a reservoir or infiltration system.

Main elements:

supporting structure;

network;

upper and side stretches;

lower gutter;

filter;

pipeline;

tank;

overflow;

flushing system;

protection from wind and ice.

8. Choosing a location for the mist eliminator

The right location is more important than the size of the structure.

It is necessary to take into account:

fog frequency;

direction of the wet wind;

wind speed;

droplet size;

height of the cloud layer;

comb shape;

turbulence;

access for maintenance;

soil stability;

risk of lightning;

ice load;

impact on birds;

direction of collected water.

The most promising places are where:

the fog moves in a steady stream;

there is no excessive turbulence;

the air flow is not blocked in front of the structure;

there is a safe foundation;

The collected water can be used by gravity.

9. Grid orientation

The working plane is usually located approximately across the main direction of the fog wind.

But in the mountains the wind is often:

changes direction;

deflected by the relief;

goes at an angle;

moves up the slope;

forms vortices behind the ridge.

Therefore the following are possible:

rotary modules;

multifaceted structures;

V-shaped patterns;

several small nets;

radial installations;

Mist eliminators designed for seasonal applications.

One large fixed wall may be less efficient and less stable than several independent modules.

10. Mesh permeability

The mesh should not completely block the air.

Surface too dense:

increases wind load;

forces the flow to bypass the structure;

creates strong turbulence;

damaged by storm;

may be less effective at capturing some droplets.

A mesh that is too open allows drops to pass through without sufficient impact.

The optimal structure depends on:

droplet size;

wind speed;

fiber thickness;

cell shapes;

wettability of the material;

surface contamination.

11. Large and small systems

Small autonomous modules

Advantages:

easier to repair;

less wind load;

can be installed in a mosaic pattern;

easier to change orientation;

failure of one element does not stop the system.

Large mesh installations

Advantages:

potentially larger collection;

unified water collection system;

simpler centralized control.

Flaws:

large sail area;

high risk of cascading damage;

complex foundation;

high ice load;

noticeable impact on the landscape and animals.

For abnormally windy ridges, a distributed modular architecture is preferable.

12. Hybrid living system

The most sustainable solution is a combination of artificial fog filters and vegetation.

The sequence could be as follows:

the artificial net collects the first volumes of water;

water is directed to protected plantings;

shrubs create a microclimate;

mosses and groundcover plants retain moisture;

vegetation gradually becomes a natural fog collector;

the need for an artificial system is decreasing.

In this case, the artificial structure functions not as a permanent replacement for the ecosystem, but as a tool for its launch.

13. Using collected water

The collected water can be sent to:

primary rooting of plants;

high-altitude nurseries;

emergency watering;

watering places for wild animals;

fire-fighting tanks;

technical needs;

feeding small damp areas;

slow infiltration.

Priority should be given not to open storage, but to:

closed tanks;

underground tanks;

shaded storage tanks;

soil infiltration;

drip feed to the roots.

An open body of water on a windy ridge can lose a significant portion of its water through evaporation.

14. Quality of foggy water

Foggy water is not always clear.

It may contain:

sea ​​salts;

dust;

combustion products;

industrial aerosols;

heavy metals;

microorganisms;

mesh particles;

organic contaminants;

bird droppings.

Therefore, the application depends on the quality.

For infiltration and plants

Coarse filtration and salinity control may be required.

For animals

Regular cleaning and protection of the tank is required.

For drinking purposes

Laboratory analysis, filtration and disinfection are required.

The name "fog water" does not automatically mean "drinking water".

15. Sea fog and salts

On coastal ridges, droplets may contain sea salt.

Moderate salt input is natural for coastal ecosystems, but artificial concentration can cause:

soil salinization;

damage to sensitive plants;

equipment corrosion;

deterioration of water quality;

accumulation of salts in reservoirs.

It is necessary to control:

electrical conductivity of water;

chloride content;

seasonal change in salinity;

washing of the soil by rain;

Salt tolerance of plants.

Salt or highly mineralized water must not be directed uncontrollably into fresh spring areas.

16. Dew as a local resource

Dew rarely produces large volumes of water suitable for centralized storage, but it is important for the microenvironment.

It can be supported through:

maintaining nighttime surface cooling;

open areas of the sky;

rough materials;

ground cover vegetation;

stone surfaces;

mosaic structure;

reduction of night overheating.

A dense, tall canopy can reduce dew formation on the soil by limiting radiative cooling. Therefore, open and closed areas should alternate.

17. Condensation surfaces

For additional dew collection the following can be used:

inclined panels;

special films;

stone slabs;

roofs;

metal surfaces;

radiation-cooled materials.

The condensate flows into the gutter and then into the storage tank.

Efficiency depends on the ability of the surface to cool below the dew point at night.

Such systems work better when:

clear sky;

high night humidity;

moderate wind;

absence of strong thermal radiation from the ground and buildings.

18. Stones as moisture collectors

Placers of stones and individual boulders participate in the water balance.

They:

cool down at night;

collect dew;

protect the soil from the sun;

create damp cracks;

direct the drops to the base;

support mosses and lichens;

reduce evaporation underneath them.

Stone mulch is especially useful in dry, windy areas, but should not completely cover the soil or create unstable mounds.

19. Fog and soil

Even a small amount of foggy moisture becomes useful only if the soil is able to retain it.

On a compacted, destroyed or organically depleted surface, water can:

evaporate quickly;

flow down the stone;

don't get to the roots;

concentrate in the crack.

Therefore, fog collection is combined with:

turf restoration;

mulching;

introduction of local organic matter;

creation of soil pockets;

wind protection;

increasing roughness;

restoration of soil biota.

20. Fog and spring feeding

Foggy water can participate in feeding springs if:

regularly reaches the surface;

passes through vegetation;

absorbed into permeable soil;

falls into fractured rock;

does not evaporate immediately;

does not disappear with rapid surface runoff.

The contribution of a single night may be small, but repeated events can maintain the moisture content of the upper catchment.

To confirm the connection, you need to observe:

fog interception volume;

soil moisture;

groundwater level;

spring flow;

seasonal delay between events.

21. Fog and forest corridors

Mountain Forest Corridors may use the fog belt as a base for the spread of a more humid ecosystem.

The forest corridor is designed so that:

accept the damp wind;

do not create a solid wall;

collect drops in several tiers;

direct water into the soil;

support mosses and undergrowth;

move into drier communities below.

The gradual structure is especially important:

low grasses → creeping shrubs → tall shrubs → sparse trees → sheltered forest island.

22. Fog and wind-resistant architecture

To capture fog, you need wind to carry the droplets.

If you completely block the air flow with a solid wall, collection may decrease.

Therefore, the defense must:

reduce destructive speed;

maintain the movement of moist air;

increase the number of contacts with surfaces;

do not create strong turbulence;

Do not overdry the leeward zone.

The optimal system does not block the fog wind, but passes it through a sequence of semi-permeable tiers.

23. Abnormal winds

Mist eliminators operate under constant wind loads and can become dangerous during a storm.

Possible:

mesh break;

destruction of supports;

foundation tearing;

transformation of elements into flying debris;

icing;

fall on the road;

blocking of the channel;

damage to plants.

Therefore, the system is designed not only for the working fog wind, but also for maximum gusts.

Solutions:

independent small modules;

flexible fastenings;

emergency folding;

removable seasonal nets;

destructible safety inserts;

duplicated stretch marks;

limited height;

safe fall zone.

24. Icing of structures

In supercooled fog, the mesh can quickly become covered with ice.

This increases:

mass;

sail area;

load on supports;

risk of collapse;

gutter blockage;

damage to the material.

It is necessary to provide for:

mechanical ice removal;

inclined surfaces;

elastic mesh;

load cells;

emergency shutdown;

free path of falling ice;

reinforced winter fastenings.

People, vehicles or fragile equipment must not be placed under the structure.

25. Thunderstorms and lightning

Tall metal structures on exposed ridges can increase the risk of lightning strikes.

The project must take into account:

grounding;

potential equalization;

lightning protection;

sensor protection;

turning off electronics;

safe distance from tourist routes;

it is unacceptable to use the structure as a shelter.

In thunderstorm areas, low distributed modules are preferred over a single tall mast.

26. Impact on birds and insects

Large mesh structures can pose a danger to animals.

Risks:

bird collision;

entanglement;

route blocking;

bat damage;

accumulation of insects;

the appearance of predators near water points.

Measures:

highly visible mesh;

contrast markers;

refusal of thin, almost invisible threads;

limitation of the size of a solid surface;

passages between modules;

environmental monitoring;

turning off unnecessary night light.

27. Biological risks

Constant humidity near the mist eliminator can cause:

fungal diseases;

root rot;

spread of mosquitoes;

overgrowing of reservoirs;

algae accumulation;

changes in the local plant community.

Water should not stagnate in open shallow containers.

Required:

closed tanks;

regular cleaning;

controlled overflow;

protection from animals;

distribution of water over the area;

soil moisture monitoring.

28. Drought and the fickleness of fog

Fog systems cannot be considered a completely reliable source.

During dry periods the following is possible:

reduction in the number of foggy days;

the rise of a cloud layer above a ridge;

change in wind direction;

reduction of droplet size;

strengthening of dry winds;

seasonal disappearance of fog.

Therefore, mist water should be an additional element, and not the sole basis of the water supply.

It is combined with:

rainwater;

snow reserve;

soil moisture;

restoration of springs;

reservoirs;

reuse of water.

29. Fog and dew monitoring

The monitoring system includes:

standard fog collectors;

visibility sensors;

humidity meters;

temperature sensors;

anemometers;

droplet size measurement;

rain gauges;

leaf wetting sensors;

weighing containers;

flow sensors;

cameras;

water quality analysis;

surface temperature sensors;

soil moisture meters.

It is necessary to distinguish:

normal rain;

foggy collection;

dew;

frost;

condensate;

runoff from vegetation.

Without this, it is impossible to correctly assess the real contribution of horizontal precipitation.

30. Map of the Nebula Potential

A separate map is being created for Mountain Digital Twin.

She shows:

fog frequency;

seasonality;

average duration;

height of the fog layer;

direction of moist winds;

air speed;

cloud contact zones;

natural vegetation;

potential collection;

risk of icing;

water quality;

convenience of gravity feed.

After field measurements, the territory is divided into zones.

Zone A - High Potential

Regular fog, suitable wind and safe terrain.

Zone B - Seasonal Potential

Collection is only possible during certain months.

Zone C - ecological potential

There is not enough water for technical storage, but it is important for mosses, shrubs and soil.

Zone D - low potential

Fog is rare or the wind is too turbulent.

Zone E is a dangerous zone.

High risk of icing, lightning, avalanches, structural failure or harm to animals.

31. DREVO Fog & Dew Module

The digital twin consists of a module that combines:

fog forecast;

humidity;

dew point;

wind speed and direction;

surface temperature;

cloud height;

volume of collected water;

water quality;

condition of the grids;

ice load;

filling of tanks;

soil moisture;

plant needs.

The module allows you to define:

where fog is expected;

how much water can potentially be collected;

which designs are most effective;

Should the water be directed into a reservoir or directly into the soil?

when cleaning is required;

when the system needs to be folded before a storm.

32. Stages of system creation

Stage 1. Observation

Fog, wind, temperature and humidity are measured for at least one complete seasonal cycle.

Stage 2. Installation of control manifolds

Small standard grids are placed for comparison of areas.

Step 3. Water analysis

Salts, contaminants and microbiological quality are checked.

Stage 4. Pilot modules

Small independent fog collectors are being created.

Stage 5. Integration with the soil

Water is directed to protected planting and infiltration areas.

Stage 6. Creating a living system

Native plants capable of intercepting fog are planted.

Step 7: Testing extreme scenarios

Storm, icing, lightning and structural failure are assessed.

Step 8. Scaling

Only truly effective areas are expanded.

33. Performance indicators

Evaluated:

liters of water per square meter of mesh;

number of effective foggy days;

seasonal volume;

the proportion of water that reaches the reservoir;

losses through overflow and evaporation;

water quality;

changes in soil moisture;

plant survival;

increase in moss cover;

structural stability;

maintenance costs;

number of bird injuries;

ice volume;

contribution to the nutrition of springs.

The key indicator is not the maximum short-term yield, but the sustainable beneficial effect on the ecosystem.

34. What not to do

It is forbidden:

install large networks without preliminary measurements;

consider each foggy area productive;

use water for drinking without analysis;

Ignore sea salt and pollution;

build a solid wall across the storm wind;

place the structure under the eaves or on the edge of a landslide;

block the migration routes of birds;

create open stagnant reservoirs;

direct all the water to one point;

over-water an unstable slope;

calculate the system only for average wind;

ignore ice load;

replace natural fog vegetation with plastic infrastructure.

The final principle

Fog, dew, frost and cloud precipitation are a hidden part of the mountain water balance.

A properly organized system:

preserves natural fog eliminators;

restores mosses, lichens and shrubs;

uses artificial nets only where they are justified;

distributes water over stable areas;

supports soil and young plants;

takes into account water quality;

withstands storms and icing;

does not pose a threat to birds, roads or people;

gradually replaces technical elements with a living ecosystem.

A mountain ridge can collect water even when rain doesn't reach the ground. This requires not stopping the moist air, but allowing it to pass through a well-organized system of plants, topography, and semi-permeable surfaces.