= うだるように蒸し暑い。
今日は変な天気だった。朝は快晴で暑くて蒸し暑く、
その後気温が下がって今は雨。そう、6月なのにサンノゼで雨。
ただし湿気は感じるものの、気温が低いんで不快ではない。んで、ちょっと調べていて、
The dew point is the temperature the air needs to be cooled to (at constant pressure) in order to achieve a relative humidity (RH) of 100%. At this point the air cannot hold more water in the gas form. If the air were to be cooled even more, water vapor would have to come out of the atmosphere in the liquid form, usually as fog or precipitation.
The higher the dew point rises, the greater the amount of moisture in the air. This directly affects how "comfortable" it will feel outside. Many times, relative humidity can be misleading. For example, a temperature of 30 and a dew point of 30 will give you a relative humidity of 100%, but a temperature of 80 and a dew point of 60 produces a relative humidity of 50%. It would feel much more "humid" on the 80 degree day with 50% relative humidity than on the 30 degree day with a 100% relative humidity. This is because of the higher dew point.
So if you want a real judge of just how "dry" or "humid" it will feel outside, look at the dew point instead of the RH. The higher the dew point, the muggier it will feel.
NWSのサイトにこんなのが。今まで"humid"と"muggy"の違いがよくわかってなかったけれど、これでよくわかった。"humid"は「湿気が高い」様を表す表現、なんで不快さに関してはニュートラル。"muggy"は体感のconnotationも含む。で、
General comfort levels USING DEW POINT that can be expected during the summer months:
- less than or equal to 55: dry and comfortable
- between 55 and 65: becoming "sticky" with muggy evenings
- greater than or equal to 65: lots of moisture in the air, becoming oppressive
不快レベルに使えるのがこの"Dew Point"(露点)。この値が65をこえる最高に不快な状況を表すのが"oppressive"。"muggy"/"sticky"は知ってたけどその上があったとは。
