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I measured the temperature of water and found that it's less than room temperature. I think evaporation is the main reason of it. Are there any reason except evaporation for the less temperature of water?

I also noticed that the temperature difference between water and air increases when humidity decreases.

Water was on a aluminium bowl. After sometimes the water temperature increases but can't beat the air temperature

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  • $\begingroup$ please provide more information about the specifics of your observation. How much water? how long has the temperature been stable? In thermal equilibrium (long rime) they should be the same temp if there is no other heat source/sink. $\endgroup$ – anon01 Apr 22 '16 at 4:36
  • $\begingroup$ Water was on a aluminium bowl. After sometimes the water temperature increases but can't beat the air temperature $\endgroup$ – Abtahee Salekeen Apr 22 '16 at 4:40
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    $\begingroup$ I mean, put it in the question. As one of the answers states, water has a high heat capacity and thus remains at a given temperature longer. $\endgroup$ – anon01 Apr 22 '16 at 4:44
  • $\begingroup$ yes. I also know that. Because of low heat capacity air heats up faster than water. But I want to know which is the main reason of the temperature difference between air and water, evaporation or high specific heat of water $\endgroup$ – Abtahee Salekeen Apr 22 '16 at 4:47
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A possible explanation is simply that the air and water have not equilibrated due to the high heat capacity of water. It's the same reason you can jump in a lake in the early summer and it still be cold. So if you filled up a glass from the sink and measured it 15 minutes later, it's entirely possible that it would be cooler. A more detailed description of your experiment is needed.

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  • $\begingroup$ Water was on a aluminium bowl. After sometimes the water temperature increases but can't beat the air temperature $\endgroup$ – Abtahee Salekeen Apr 22 '16 at 4:40
  • $\begingroup$ @AbtaheeSalekeen: You really need to quantify "after sometimes" and "increases". For example make readings of temperature of both air and water in Celsius every 60 seconds for two hours and keep notes of time and temperature. Quantify the volume of the bowl. Measure the volume of the water and/or weigh the bowl before and after to estimate the losses due to evaporation. Etc. What are the numbers? What are possible sources of error? Are people opening & shutting doors/windows or occasionally operating machinery nearby? $\endgroup$ – RedGrittyBrick Apr 22 '16 at 10:22
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This could be explained by evaporative cooling. That would match all of the (extremely scant) information you have provided about your experimental setup and results.

If you would like a more thorough analysis of possible causes, you are going to need to write at least a couple sentences (preferably even more than that!) about your experimental setup. What was the water contained by? How did you measure the temperature of the water/air? How did you measure the humidity of the air?

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  • $\begingroup$ this is unlikely, if he has measured the temperature with a thermometer... $\endgroup$ – anon01 Apr 22 '16 at 4:37
  • $\begingroup$ Water was on a aluminium bowl. After sometimes the water temperature increases but can't beat the air temperature. My table clock measured the humidity @Ducan Harris $\endgroup$ – Abtahee Salekeen Apr 22 '16 at 4:40
  • $\begingroup$ @AbtaheeSalekeen You are saying "after some time". How long exactly did you wait to measure the temperature? Ideally you should provide a graph with temperature measurements put against exact time stamps, measuring both the temperature of water and air + the humidity. And also provide the measurement error (how precise are the tools you are using to measure temperature and humidity). $\endgroup$ – mpv Apr 22 '16 at 8:35

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