everybody doctor over here and this fair going to talk about the four mechanisms of heat exchange or heat transfer so as you can see we have radiation evaporation convection and conduction so they all work in a very similar method and that is that heat is going to flow from where there's a high concentration of it to a low concentration the four different methods are mechanisms of heat transfer just have to do it directly how it's done so let's look at each one of them so let's start here with conduction so conduction is going to be the transfer of heat between two objects that are touching each other so here we see you can guess by looking at this picture that the warm tea warm coffee whatever's in there is gonna transfer that heat from the from the mug into the finger so your fingers are gonna be warm if you're holding minds in the thermos but if you're if you're holding or warm water I think it's generally more with seats right if you sit down and the seat is real cold now it's going to actually make you colder where you sit down a seat is real hot and it's gonna make you hotter so that's conduction when two things come in direct contact with each other this is only gonna be about three percent of the heat transfer that occurs with humans so it's not not a huge deal next we have convection so you see here the wind is blowing here if imagine you have a fan blowing in your face this kind of thing convection is gonna be responsible for about 15 percent of the heat loss from a human body remember where this heat comes from just the our our metabolism generates it so this is gonna be the air surrounding us is going to kick it is going to carry heat away from us if the air is cooler than our bodies so if you think about it I think about this with wind chill right like why is it colder when it's windy well we kind of have a blanket of warmth around us and what the wind does is blows that blanket off and that's why it's so much colder when it's windy so the wind chill would be it would be an example of of increased convection moving this warm air away from our bodies so we're surrounded by cooler air making this colder at least that's what I think up with convection so still not a huge huge deal the next to the last two are the ones that we pay the most attention to and the first is radiation this is going to be by far the most common way that your body loses heat is through radiation so radiation is the transfer of heat through infrared rays you see a picture of the Sun here so the Sun is basically radiating us if you're outside I think about like in the middle of July or August or something and you're outside and it feels like the Sun is literally down your neck because on these really sunny days that that heat that heat and radiation from the Sun is actually transferring heat into you and warming you up other examples of radiation so we out we're all basically radiators just like a radiator in a room can warm a room up we're basically radiators which is why if you put a large group people together the temperature of the room would go up because we're all just sitting here furnaces just pouring out heat so remember that radiation is the key way that we lose body heat and that's why we just radiate into our environment in with the infrared rays this is also why if you use like infrared cameras you can see you can see us because we light up because of this infrared energy being released from our bodies and lastly we have evaporation so normally evaporation is around 20% of the heat that's lost by human body this is especially so I would say the key thing here is radiation is the key way we lose body heat but evaporation is the key way we cool down so if we're overheating because it's hot out or we're exercising evaporation or maybe it's better to call it sweat evaporation is the main way that we cool our bodies off so it has to do with the fact that it takes a lot of energy to vaporize water to to remove water and evaporate it into the environment and as it does so it's gonna pull a lot of water with it now that's how sweating works but the key with sweat besides the fact that it's the primary way we cool our bodies down when we're exercising is sweat evaporation is going to be dependent on humidity in a low humidity situation or environment almost all the sweat you produce will be evaporated and take heat with it but if it's humid there's already so much moisture in the atmosphere that your sweat is going to pull off of you rather than being evaporated this is why it's up to nearly say it's up to 27 times harder to cool your body down when it's human and we all know that 90 degrees with low humidity doesn't feel anything like 90 degrees with high humidity and that's why if you're concerned about dehydration or losing too many electrolytes super important the more human it is the more the more liquid you can consume you can lose two 3,000 milligrams of sodium in an hour from sweating but if you're if you're sweating and it's not being evaporated which means that you're sweating and it's not cooling you off your body's going to regenerate more and more sweat so in a human environment you make way more sweat but it's actually less effective and that's why you got to be careful with dehydration because and then if you stop sweating that's when you get in serious concerns with heatstroke because without this process how are you gonna cool your body and your core temperature is going to climb and that could be life-threatening alright so those are the four mechanisms of heat transfer just remember that radiation is the primary one and then evaporation or sweat evaporation is the primary way we cool if we're exercising or we're getting hot I hope this helps have a wonderful day be blessed