Plastic tent platforms are madness

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Re: Plastic tent platforms are madness

Postby Neo » Wed 02 Jun, 2021 2:25 pm

I can guarantee/confirm that the more moisture there is in the ground the more condensation I get in a vestibule, tarp or tent fly. Also under the floor or ground sheet, except maybe a bum sized dry patch.
Along with other conditions.
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Re: Plastic tent platforms are madness

Postby ghosta » Thu 03 Jun, 2021 3:30 pm

[quote="Scottyk"]Tent condensation is is the result of humidity and dew point.
What causes those two factors to be ideal for water to condensate on your tent walls is the important bit.


Just to clarify things, dew point is simply a measure of the humidity...
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Re: Plastic tent platforms are madness

Postby Scottyk » Thu 17 Jun, 2021 10:33 am

ghosta wrote:
Scottyk wrote:Tent condensation is is the result of humidity and dew point.
What causes those two factors to be ideal for water to condensate on your tent walls is the important bit.


Just to clarify things, dew point is simply a measure of the humidity...

Sorry, but no
Dew point is the temperature air needs to be cooled to be be considered saturated with water vapor.
If the humidity is high the air doesn't need to be cooled as much to reach saturation.
The attached picture shows a psychometric chart that is commonly used by HVAC industry types to work out how to make humans comfortable indoors.
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Re: Plastic tent platforms are madness

Postby ghosta » Fri 18 Jun, 2021 3:54 pm

Seems you are a little muddled on this topic so I'll explain in simple terms so you can understand the concept of humidity and dew point.

Humidity: moisture held in the air.

Dew Point: measure of the amount of moisture held in the air(ie measure of humidity)

Another way of measuring the amount of moisture held in the air is the "Relative Humidy"

As a retired professional firefighter the concept of humidity and how to measure it was absolutely fundamental to the job. Firefighters need this information to predict bushfire danger ratings,fire spread, flame height etc.

I would be happy to explain more if there is still things you dont understand about the topic.
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Re: Plastic tent platforms are madness

Postby Tortoise » Fri 18 Jun, 2021 4:25 pm

Those simple terms don't help me, I'm afraid ghosta. Everything I've read says that dew point is a temperature, and humidity is how saturated the air is with moisture. Of course they are inextricably related, but a temperature is measured in degrees, and humidity is (I think) expressed as a %. Therefore they are not the same thing.
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Re: Plastic tent platforms are madness

Postby ghosta » Fri 18 Jun, 2021 4:52 pm

Heres a link which explains it in abit more detail.

https://www.chicagotribune.com/weather/ ... olumn.html
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Re: Plastic tent platforms are madness

Postby Neo » Fri 18 Jun, 2021 5:34 pm

Think of it as the temperature, at which point, the air humidity results in dew?

It varies, don't ask me why! I love it when there is now dew on my tent.

Edit: NO dew on my tent :)
Last edited by Neo on Sat 19 Jun, 2021 6:06 pm, edited 1 time in total.
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Re: Plastic tent platforms are madness

Postby Scottyk » Sat 19 Jun, 2021 6:01 pm

ghosta wrote:Heres a link which explains it in abit more detail.

https://www.chicagotribune.com/weather/ ... olumn.html


I think you might be a bit muddled..
The link you have provided gives an excellent explanation of dew point and reinforces the fact that dew point is as I have described it. Absolutely not just a measure of humidity. The the article you cited is below, I have pasted it here for clarity. I have underlined the important bits.

"Relative humidity and dew point are indeed concerned with the amount of water vapor in the air, but there are differences. Dew point is the temperature at which the air is saturated (100 percent relative humidity). It is dependent on only the amount of moisture in the air. Relative humidity is the percent of saturation at a given temperature; it depends on moisture content and temperature. As air is heated, its ability to hold water vapor doubles with about every 11 degree increase in temperature. If air is at 100 percent relative humidity at 60 degrees but is heated to 93 degrees, its relative humidity decreases to about 33 percent. Its dew point remains at 60 degrees."
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Re: Plastic tent platforms are madness

Postby ghosta » Sat 19 Jun, 2021 7:37 pm

Not really sure how anyone could confuse themselves as you have, it really is pretty simple.

Relative Humidity and Dew Point are both ways of describing the amount of moisture in the air, which is humidity.

Let leave it at that, i dont think there is any point trying to explain it to you any further, there really isnt anymore to explain.

Lets hope there are no more plastic tent platforms installed.
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Re: Plastic tent platforms are madness

Postby north-north-west » Sat 19 Jun, 2021 7:48 pm

ghosta, you're the one who is getting this wrong.

Humidity is measured in a percentage. Dew point is measured as a temperature. They are not just different words for the same thing.
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Re: Plastic tent platforms are madness

Postby Warin » Sat 19 Jun, 2021 8:55 pm

north-north-west wrote:Humidity is measured in a percentage. Dew point is measured as a temperature. They are not just different words for the same thing.


To convert from one to the other the present temperature is required, in this regard Dew Point without that 'present temperature' information lacks the ratio information that humidity already contains. So they are related.

As a rough guide, a 1 °C temperature change will change the humidity by 5%.

Knowing only the Dew Point tells you nothing about the present humidity/temperature, it only gives you the temperature at which condensation will occur.
Knowing only the humidity does tell you how much the temperature must drop before condensation takes place and how 'sweaty' the present conditions are.
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Re: Plastic tent platforms are madness

Postby north-north-west » Sun 20 Jun, 2021 8:24 am

Related does not mean they are the same. Speed and acceleration are related but they are different things.
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Re: Plastic tent platforms are madness

Postby ghosta » Sun 20 Jun, 2021 8:57 am

NorthNorthwest you are not using a valid analagy. Heres a better one which might help you understand that both RH and Dew Point measure humidity but in different ways.

If I asked how much water is in that tank, one answer might be "half full" and another answer "10cm from the top". These answers cannot be converted without further information in the same way celcius and farenheight can.

I realise measuring humidity can be confusing for the layman, the link I posted in an earlier post should help.
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Re: Plastic tent platforms are madness

Postby north-north-west » Sun 20 Jun, 2021 10:06 am

They measure different aspects of humidity, and I wasn't using the speed/acceleration reference as an analogy to the humidity issue, simply as a way of pointing out that being related is not being the same. Once again, you're applying inappropriate interpretations.
I don't need any more references, I understand humidity and dew point. I also understand the gist of this conversation better than you. You might want to consider the possibility that people disagreeing with you are not necessarily wrong. They may be better informed.
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Re: Plastic tent platforms are madness

Postby ghosta » Sun 20 Jun, 2021 2:35 pm

Getting closer...they both measure EXACTLY the same thing..humidity, or the amount of moisture in the air.I guess that the fact that RH is expressed as % and DP as a temp makes some think different things are being measured.
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Re: Plastic tent platforms are madness

Postby matagi » Sun 20 Jun, 2021 2:53 pm

I would hope the Bureau of Meteorology knows what it's talking about.

https://media.bom.gov.au/social/blog/13 ... dew-point/
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Re: Plastic tent platforms are madness

Postby Rexyviney36 » Mon 21 Jun, 2021 11:01 am

Came for the platforms, stayed for the science...
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Re: Plastic tent platforms are madness

Postby Mark F » Wed 23 Jun, 2021 6:15 pm

ScottyK has the best answer. Humidity is the percentage of water vapour that air contains with 100% being the maximum possible water vapour content at the current temperature. The maximum amount varies with temperature with cold air being able to contain less water vapour than hotter air. The Dew Point is the temperature at which humidity reaches 100%.
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Re: Plastic tent platforms are madness

Postby Lophophaps » Wed 23 Jun, 2021 7:17 pm

It would be good to focus on the science and cite references. This is one of several I found that all say the same thing.
https://www.livescience.com/43269-what- ... point.html
"The dew point is the temperature at which air is saturated with water vapor, which is the gaseous state of water.

"When air has reached the dew-point temperature at a particular pressure, the water vapor in the air is in equilibrium with liquid water, meaning water vapor is condensing at the same rate at which liquid water is evaporating.

"Below the dew point, liquid water will begin to condense on solid surfaces (such as blades of grass) or around solid particles in the atmosphere (such as dust or salt), forming clouds or fog."

If anyone has a good reference that varies this, please cite it. If not I think it's time to move on.

I would like to see platforms flat in one direction and going down left and right in the other direction, like a very shallow tile roof. This would make precipitation go away from the tent. I got wet at one Overland Track platform when snow fell and slid over the groundsheet. Some platforms such as the ones at Cope Hut in Victoria defy attempts to easily secure a tent. I like ground better.
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Re: Plastic tent platforms are madness

Postby Warin » Wed 23 Jun, 2021 8:59 pm

Lophophaps wrote:I would like to see platforms flat in one direction and going down left and right in the other direction, like a very shallow tile roof. This would make precipitation go away from the tent.


That assumes there is no wind to blow water uphill :oops:

I would suggest the platform have a hi point to the north west, with a mid point to the south east and lowest points to the north east and south west... should not be much of a difference between those points (? 6 mm per meter of run?). Of course the orientation could be changed to match the normal rain direction for the location.
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Re: Plastic tent platforms are madness

Postby Lophophaps » Thu 24 Jun, 2021 7:58 am

Warin, a good point. The concepts we have raised can be used to adjust the angle of the platform for each situation.

Another option is to have a windbreak on three sides to keep off the wind. A big roof would keep off the rain. If the wind comes from all directions a fourth windbreak with a door may be needed.
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