What is condensation? Apart from being a fact of nature condensation is water that collects as droplets on a cold surface when humid air is in contact with it.
How does it affect tents? At some point in time we will all experience some level of condensation. It is largely to do with the conditions both external and internal to your tent. Some of these conditions we can control, some we cannot.
The idea of a dual skin tent system is to provide not only protection from wind and rain but also from condensation. The outer layer or tent fly is a waterproof barrier designed to stop rain from entering your tent system. The inner section is designed to be a barrier from the possibility of condensation should it occur.
The area between the inner and outer layers also acts as an insulation barrier. The effectiveness of this insulation can also play a part in condensation.
If there is little or no breeze this will impact the effectiveness of ventilation. Whilst it’s good to camp in a sheltered area away from high wind it can be favourable to camp where there is some breeze.
- Tent selection
- Site selection
- Sleeping Bag and mat selection
Arguably one of your most important “controllable factors” is tent selection. With a variety of brands and styles available it can be hard to arrive at a decision. If heading into the mountains and in particular Alpine areas it is important to cater for the potential of adverse conditions. A 4-season tent would be most suitable for winter, alpine and just about all of south-eastern mainland Australia and Tasmania.
Utilising the features of your tent can improve your chances of avoiding condensation greatly. Often 4 season tents will have mesh panels and vents positioned to encourage cross-flow ventilation or in some cases roof top ventilation. If conditions allow it can even help to have the vestibule doors open to allow for maximum air flow.
Another important factor but not always in our control, given we often like to camp somewhere picturesque. Occasionally there are times where people camped within the same area experience different micro climates so there is still a lot to be said for site selection even if it is near a river or a lake.
Often near bodies of water are some treed or wooded areas which can provide shelter from rain and dew. It is however very important to consider falling limbs when camping in treed areas. Foliage can protect you from a heavy dew or frost which descends in cold layers directly to the ground.
Being high up on ridgelines can be quite breathtaking but care needs to be taken with regard to wind. Coming downhill slightly can provide some protection in these areas.
There is an element of truth in the “high and dry” theory but higher does not always mean dryer. Head up hill from creeks, streams and rivers to avoid unnecessary damp conditions.
Avoiding areas where water might pool or flood is another thing to consider when pitching your tent so as to avoid sleeping in puddles or potential watercourses.
Have a walk around your intended camp site and see if you can feel the breeze in certain spots over others. If it's safe to camp in a sheltered treed area, it will help assist in a more comfortable night sleep.
With everything mentioned so far it can be worth paying attention to what other gear you have in your sleep system. If your sleeping bag is over compensating for the conditions you might find you generate some extra heat within your tent especially if there are two of you. If this is the case with your sleeping bag you may benefit from zipping sections of it open to vent some excess body heat. Having a 3 season bag for warmer weather and a 4 season sleeping bag for colder months can be the ideal fix in this situation.
In very cold (Alpine) situations be prepared for the condensation from your breathing to settle on the inside of your tent and freeze, only to melt and rain on you and your gear when the tent warms up the following day. In a humid environment such as we find in Nepal, scraping that frozen layer off the inside of the tent is an important morning ritual. On the other hand the very low humidity of the Andes means the temperature can be as low as -15C but there is no evidence of frost inside or outside of the tent. (the super low humidity creates other challenges like hydration).
Unless you are an absolute ‘fair weather’ hiker the ‘weather’ shall be considered the “uncontrollable factor”. Weather can also change dramatically and unpredictably especially in the mountains.
Precipitation is basically any moisture making it’s ways towards the ground, be it in the form of rain, snow, hail, sleet or mist.
Atmospheric Pressure the pressure exerted by the weight of the atmosphere. This is usual relative to the pressure at sea level.
Humidity is the amount of water vapour in the air. Commonly measured in %.
All air contains water, usually as invisible vapour. At night the ground cools chilling the air in contact with it. Cold air can’t hold as much water as warm air and so there comes a point when the air touching the ground releases the water it can no longer hold. At this precise moment, dew drops form. When the sun warms the ground and the air above it, the water can be re-absorbed again and the dew evaporates.
Dew Point is the atmospheric temperature ( varying according to pressure and humidity) below which water droplets begin to condense and dew can form.
It is very hard to predict the dew point unless you camp under a weather station. There are some useful calculators which allow you to get close to knowing the dew point in particular areas however you would need to know the temperature, atmospheric pressure and humidity reading for the area you are in.
Considering we cannot control the weather it makes sense to control those things that we can. A tent appropriate for the conditions, sleeping gear appropriate to the conditions, site selection and checking the weather so you are aware of the conditions you might encounter and thus cater for. Remember 4 season conditions can pop up any time of the year in some places. Even in Australia we have experienced snow in December in the Snowy Mountains. As the saying goes: it's better to have it and not need it, than to need it not have it.