Weather & Atmospherics

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General principles of operation
Weather comes in four main forms: wind, rain, snow and fog. The principles and details are quite different for each.

Wind – Wind machines are usually either electric or petrol driven. The machine is started up slowly (instant wind needs more equipment) and is positioned as close as possible to where the wind is required. Wind dissipates and slows very quickly, hence the closeness; it also means you generally need a bigger machine than you think.

Rain – Water is either pumped from a bowser or fed from water mains (like firemen). It is discharged from a variety of end fittings to get different effects and densities of rain. If the rain is required in a studio a shallow tank is made (low cost) to collect the water. The Fire Brigade can be hired to make rain on a large scale, but they are not used to working on film sets and guess what happens if there is a fire elsewhere?…

Snow – There are (and this is not an Eskimo related fact) about 120 different kinds of snow, so describe the effect you are looking for, how long it needs to last, does it settle on actors or disappear etc, then the right kind can be selected. Check this is right for you – see a sample. Artificial snow is generally a powder, flakes of paper or plastic, salt, or foam sprayed onto the area, they all act differently.

Fog – Smoke machines are usually electric or gas powered, some small ones are hand-held. The smoke comes in different densities, from very light to very heavy, the lighter the smoke, the quicker it disappears. Smoke usually rises but can be made to sit low on the ground. Clever use of machines and smoke compounds can make effects from a low autumn mist to complete pea soup.

First considerations
Accessibility of equipment is important, much weather making equipment is heavy and cumbersome. In most respects, weather effects produced inside are a lot easier because you do not need to consider what the real weather is doing. If you are outside check the likely weather conditions, the hardest to deal with being wind, it will blow away snow and smoke/fog, it will alter the direction and course of rain and wind machines will not blow into a strong wind, they cancel each other out. As a general rule the earlier in the day, the lower the wind velocity, so consider as early a shoot as you can manage.

Buildings and the lay of the land can cause unusual local conditions so be careful. When making wind it will blow anything on the ground, so a dry sandy beach is a bad place for an actor looking into a wind machine. It can also cause continuity problems. A handy source of water is required for rain effects or it will need to be shipped in and is therefore more expensive. If it rains during your shoot (the real stuff) you may need to bring in equipment for‘wet-down’ continuity.

Budget expectations
Weather effects are generally not too expensive if you want a little rain, wind or smoke; snow tends to cost a little more. However, real weather does what it wants and can contradict your needs, so you may not get the shots you wanted; an additional cost. If water is to be drawn from a mains standpipe then water board clearance and personnel need to be sought at a modest cost; usually directly through production.

Questions to ask
Can I see a showreel and example job? – Weather effects are never straightforward.
What power will be required?
Will the effects crew require assistance getting the equipment into position? – Describe
accurately the location and your requirements, if at all possible meet at the location to clarify
your desires, (a reccee is recommended).

Problems to watch out for and things to do
-Check local Met Office reports, because the real weather is your enemy.
-Make sure the equipment is powerful/big enough.
-Noise can disrupt communications.
-Wind can pick up flying debris and alter sets in a dangerous or annoying way.
-Make sure you have a ready water supply for rain jobs, tonnes of water are likely to be used.
-Rain must be lit properly or it won’t be seen, and must also come from one direction only or it looks odd. On windy days crew and equipment will get wet as spray gets blown.
-Foam snow is really bad for plants and needs a water supply, but disappears after a time, paper, plastic or powder snow takes a great deal of effort to clean up. Hard foam snow has health and safety problems during application.
-Wind equipment is noisy and fog equipment can obscure the operator’s view of others, so communications equipment may also be required.
-Weather effects can be dangerous to members of the public, so try to keep them from interfering with each other, especially so with smoke and roads.

Know the jargon
Bowser A mobile water tank
Cracked oil The hazy air seen in stadiums etc to make the lights show clearly – inside use only
Ducted fan Directional wind machine
Dry ice Frozen carbon dioxide used for low smoke effects
Foam snow Snow made by mixing water and a foam solution and then spraying it through special nozzles
Godiva Large petrol powered water pump
Grain blower Small directional wind machine, also useful for moving confetti etc.
Hydrant/standpipe The water mains that firemen tap into
Low smoke Smoke made to lie low to the ground
Mini mist Standard small smoke machine
Paper snow Exactly as described
Pea souper Small, dry ice fog machine – small coverage
Rain head A sprinkler fitting on the end of a pipe
Rain lance A pipe with holes drilled along it or at the end of it
Salt Dendritic salt settled snow on the ground, will kill plants – now largely superceded but still discussed
Smoke oil/oil The liquid used to make smoke
Snow candles Pyrotechnic devices which emit “snow flakes”
Submersible A pump that is submerged in a water supply
VW/VeeDub Fairly standard medium sized petrol wind machine operated by a Beetle engine, these always require an operator
Wet down Spray an area with water as if it has been raining