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Answer
Are you backpacking or car camping? The former stresses compact packed-size and light weight, while the latter favors extra floor space and stand-up height.
Are you a fair-weather camper or all-weather camper? If the latter, make sure your tent has a full-coverage rain fly, one-piece bathtub floor, and lots of guy-down points. Pay attention to reviewer's reports of performance during rain.
Ignore the capacity ratings for tents, there are no true standards. Instead, figure out how much space you and your tent-mates need to layout and sleep comfortably, leaving a little extra room to maneuver. Then get a tent that provides least that much floor space. Remember that sloping walls take away as much as 12" from each dimension unless you want to be pressed against the wall.
Are you backpacking or car camping? The former stresses compact packed-size and light weight, while the latter favors extra floor space and stand-up height.
Are you a fair-weather camper or all-weather camper? If the latter, make sure your tent has a full-coverage rain fly, one-piece bathtub floor, and lots of guy-down points. Pay attention to reviewer's reports of performance during rain.
Ignore the capacity ratings for tents, there are no true standards. Instead, figure out how much space you and your tent-mates need to layout and sleep comfortably, leaving a little extra room to maneuver. Then get a tent that provides least that much floor space. Remember that sloping walls take away as much as 12" from each dimension unless you want to be pressed against the wall.
How Does A Sleeping Bag Insulate?
trebor_reg
I recently had an argument with my science teacher about a Q i supposedly got wrong in my test.
A sleeping bag insulates by Preventing:
A)Conduction_________________He says this is right
B)Convection_________________I say this is right
C)Radiation__________________He says this is right
D)Insulation
Of course the question is asking which one is most correct
Answer
How does a sleeping bag keep me warm?
Warmth in a sleeping bag is a direct result of keeping the warmth generated by your body inside the bag, while keeping the cold air outside.
Three factors that affect warmth...
1. Insulation - Since air is a poor conductor of heat, the trapped air within the insulation acts like a thermal barrier between you and the cold air outside the bag by not letting your body heat escape from the bag. The insulation traps air and keeps it from moving around, hence the phrase "dead air". The more dead air you can trap, the more you will be insulated from the cold, and the warmer your bag will be.
2. Construction - How the sleeping bag is stitched or sewn also has a lot to do with the heat integrity of the bag. For example, if the outer liner material is stitched through the insulation to the inner liner material, this construction will not perform as efficiently as if the outer material is quilted to the insulation. This means the stitch lines don't go all the way through and thus, will not allow heat to escape through stitch holes.
3. Environment - The use of a sleeping mat or pad can improve the thermal performance of your sleeping bag by as much as 10° F, not to mention the added benefit when using a tent or bivy shelter. The advertised temperature ratings are only guidelines and assume the use of a ground pad and the user being inside a shelter.
The body loses heat three ways...
1. Convection takes place when warm air moves away from the body through openings in the bag and by air movement in large gaps between the body and the bag.
2. Radiation is the process of radiant energy leaving the body and passing through the material of the bag.
3. Conduction is the transfer of body heat through still air and through the materials that make up the insulator.
http://www.slumberjack.com/faq.asp#howwarm
This page suggests that a sleeping bag prevents heat loss from Convection, Conduction, Evaporation, and Radiation while it explicitly states, "The most important losses for a sleeping person are conduction and convection." http://www.bask.info/info/papers/heat_balance_and_temperature_ratings_for.html
This is from REI's website:
"Here are explanations of thermodynamic terms sometimes used when discussing sleeping bags:
* Convection: When your warm body comes in contact with cold air, the air close to you heats up while you lose warmth. A sleeping bag works to offset convection by trapping a layer of warmed air close to your body.
* Conduction: Heat transfer caused by physical contact. Sleep on frozen ground and you are susceptible to losing body heat due to conduction. The ground is trying to reduce your body temperature and your body is trying to warm the ground. To win this battle, sleep on a good pad.
* Radiation: The sensation you feel when standing near a fire or a block of ice is radiation. A warm body radiates more energy than it absorbs; the environment absorbs more than it radiates."
http://www.rei.com/online/store/LearnShareDetailArticlesList?categoryId=Camping&url=rei/learn/camp/howslbags4f.jsp
There's a huge explanation here as an excerpt from the NOLS Wilderness First Aid manual that explains how heat is lost: http://www.nols.edu/store/product.php?productid=16378&cat=286&bestseller
I'd say your instructor needs some instruction.
How does a sleeping bag keep me warm?
Warmth in a sleeping bag is a direct result of keeping the warmth generated by your body inside the bag, while keeping the cold air outside.
Three factors that affect warmth...
1. Insulation - Since air is a poor conductor of heat, the trapped air within the insulation acts like a thermal barrier between you and the cold air outside the bag by not letting your body heat escape from the bag. The insulation traps air and keeps it from moving around, hence the phrase "dead air". The more dead air you can trap, the more you will be insulated from the cold, and the warmer your bag will be.
2. Construction - How the sleeping bag is stitched or sewn also has a lot to do with the heat integrity of the bag. For example, if the outer liner material is stitched through the insulation to the inner liner material, this construction will not perform as efficiently as if the outer material is quilted to the insulation. This means the stitch lines don't go all the way through and thus, will not allow heat to escape through stitch holes.
3. Environment - The use of a sleeping mat or pad can improve the thermal performance of your sleeping bag by as much as 10° F, not to mention the added benefit when using a tent or bivy shelter. The advertised temperature ratings are only guidelines and assume the use of a ground pad and the user being inside a shelter.
The body loses heat three ways...
1. Convection takes place when warm air moves away from the body through openings in the bag and by air movement in large gaps between the body and the bag.
2. Radiation is the process of radiant energy leaving the body and passing through the material of the bag.
3. Conduction is the transfer of body heat through still air and through the materials that make up the insulator.
http://www.slumberjack.com/faq.asp#howwarm
This page suggests that a sleeping bag prevents heat loss from Convection, Conduction, Evaporation, and Radiation while it explicitly states, "The most important losses for a sleeping person are conduction and convection." http://www.bask.info/info/papers/heat_balance_and_temperature_ratings_for.html
This is from REI's website:
"Here are explanations of thermodynamic terms sometimes used when discussing sleeping bags:
* Convection: When your warm body comes in contact with cold air, the air close to you heats up while you lose warmth. A sleeping bag works to offset convection by trapping a layer of warmed air close to your body.
* Conduction: Heat transfer caused by physical contact. Sleep on frozen ground and you are susceptible to losing body heat due to conduction. The ground is trying to reduce your body temperature and your body is trying to warm the ground. To win this battle, sleep on a good pad.
* Radiation: The sensation you feel when standing near a fire or a block of ice is radiation. A warm body radiates more energy than it absorbs; the environment absorbs more than it radiates."
http://www.rei.com/online/store/LearnShareDetailArticlesList?categoryId=Camping&url=rei/learn/camp/howslbags4f.jsp
There's a huge explanation here as an excerpt from the NOLS Wilderness First Aid manual that explains how heat is lost: http://www.nols.edu/store/product.php?productid=16378&cat=286&bestseller
I'd say your instructor needs some instruction.
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Title Post: How to Pick Your Next Camping Tent?
Rating: 100% based on 9998 ratings. 5 user reviews.
Author: Unknown
Thanks For Coming To My Blog
Rating: 100% based on 9998 ratings. 5 user reviews.
Author: Unknown
Thanks For Coming To My Blog
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