测量空气相对湿度，通常是同时用干球温度计和湿球温度计测量气温，用干球温度减去湿球温度得到干湿差，再根据如下的相对湿度表查出空气相对湿度。由表中数据可知，下列判断正确的是（ ）
| | 干球温度 | -5.0℃ | 0.0℃ | 5.0℃ | 10.0℃ | 15..0℃ | 20.0℃ | 25.0℃ | 30.0℃ | 35.0℃ |
| 干湿差 | 1.0℃ | 77% | 82% | 86% | 88% | 90% | 91% | 92% | 93% | 94% |
| 2.0℃ | 54% | 65% | 71% | 76% | 80% | 82% | 83%。 | 86% | 87% |
| 3.0℃ | 32% | 47% | 58% | 65% | 70% | 74% | 76% | 79% | 81% |
| 4.0℃ | 11% | 31% | 45% | 54% | 61% | 66% | 68% | 73% | 75% |
| 5.0℃ | | 15% | 32% | 44% | 52% | 56% | 61% | 67% | 69% |
