| | | | | | | | | 50 | 0.360 | 29 | 27 | 23 | 19 | 15 | 9 | +2 | -8 51 | 0.373 | 31 | 28 | 25 | 21 | 17 | 12 | 6 | -3 52 | 0.387 | 32 | 29 | 26 | 23 | 19 | 14 | 9 | +1 53 | 0.402 | 34 | 31 | 28 | 24 | 21 | 16 | 11 | 5 54 | 0.417 | 35 | 32 | 29 | 26 | 23 | 19 | 14 | 8 55 | 0.432 | 36 | 34 | 31 | 28 | 24 | 21 | 16 | 11 56 | 0.448 | 38 | 35 | 32 | 29 | 26 | 23 | 19 | 14 57 | 0.465 | 39 | 36 | 34 | 31 | 28 | 24 | 21 | 16 58 | 0.482 | 40 | 38 | 35 | 32 | 29 | 26 | 22 | 18 59 | 0.499 | 42 | 39 | 37 | 34 | 31 | 28 | 24 | 20 | | | | | | | | | 60 | 0.517 | 43 | 41 | 38 | 35 | 32 | 29 | 26 | 22 61 | 0.536 | 44 | 42 | 39 | 37 | 34 | 31 | 28 | 24 62 | 0.555 | 46 | 43 | 41 | 38 | 35 | 32 | 30 | 26 63 | 0.575 | 47 | 45 | 42 | 40 | 37 | 34 | 31 | 28 64 | 0.595 | 48 | 46 | 44 | 41 | 38 | 36 | 33 | 30 | | | | | | | | | 65 | 0.616 | 49 | 47 | 45 | 43 | 40 | 37 | 34 | 31 66 | 0.638 | 51 | 48 | 46 | 44 | 42 | 39 | 36 | 33 67 | 0.661 | 52 | 50 | 48 | 45 | 43 | 40 | 38 | 35 68 | 0.684 | 53 | 51 | 49 | 47 | 44 | 42 | 39 | 36 69 | 0.707 | 54 | 52 | 50 | 84 | 46 | 43 | 41 | 38 | | | | | | | | | 70 | 0.732 | 55 | 53 | 51 | 49 | 47 | 45 | 42 | 40 71 | 0.757 | 57 | 55 | 53 | 51 | 49 | 46 | 44 | 41 72 | 0.783 | 58 | 56 | 54 | 52 | 50 | 48 | 45 | 43 73 | 0.810 | 59 | 57 | 55 | 53 | 51 | 49 | 47 | 44 74 | 0.838 | 60 | 58 | 56 | 54 | 53 | 50 | 48 | 46 | | | | | | | | | 75 | 0.866 | 61 | 60 | 58 | 56 | 54 | 52 | 50 | 47 76 | 0.896 | 62 | 61 | 59 | 57 | 55 | 53 | 51 | 49 77 | 0.926 | 64 | 62 | 60 | 58 | 56 | 54 | 52 | 50 78 | 0.957 | 65 | 63 | 61 | 59 | 58 | 56 | 54 | 52 79 | 0.989 | 66 | 64 | 62 | 61 | 59 | 57 | 55 | 53 | | | | | | | | | 80 | 1.022 | 67 | 65 | 64 | 62 | 60 | 58 | 56 | 54 ------+-------+-----+-----+-----+-----+-----+-----+-----+----- The temperature at which dew forms will depend on the amount of moisture present in the air, but with a definite humidity and air pressure it will always occur at the same temperature. If the dew-point is above freezing, the dew will form as drops of water, but if it is at or slightly below the freezing point, the dew will appear as frost. _White frost_ is formed when the dew-point is only a few degrees below the freezing point. _A Black frost_ occurs when the atmospheric humidity is so low that dew does not form until the temperature is much below the freezing point.