(no subject)

[sinjun]

Busy today. No time to write up a long post. Golf yesterday - way hot, (one of those 35C +humidity=45C days, after all) and I golfed a 59. Consistent, yup.

And after that in rp ...poor Yasmin.

Comments

Re: Bleh

[damara.livejournal.com]

From various weather related sites - I started at www.theweathernetwork.com and looked from there.

If it's 3°C outside with a windchill factor of -8°C, will water freeze due to the windchill factor?
No. The freezing point of pure water is, as you know, 0°C. If the air temperature is not at or below freezing there is no way that any matter in contact with the air can fall below freezing. This is the first law of thermodynamics, and applies to all objects, liquid, solid or even a gas that is contained in a way so as not to mix with the air. Water placed in a room at 3°C cannot get colder than 3°C no matter what the wind is doing. In fact, even if the wind is howling and the water is already frozen as ice, if the temperature is 3°C the ice will melt and warm to 3°C in time.
The reason people and warm blooded animals feel a windchill is that we generate heat internally as we metabolize food and fat. When the wind is blowing and the temperatures are cold enough (as opposed to a hot summer day) our bodies lose this internally generated heat as the air flowing around us carries the heat away. The stronger the wind, the faster this heat loss occurs and the more we "feel" the cold.

Heat is a form of energy which is measured in Joules. The rate at which heat is generated or lost can be measured in Joules per second, which is exactly the same as Watts. In much of Western Canada it is common to describe windchill not as an equivalent (cold) temperature but in the form of Watts per square metre.

A windchill of 2200 Watts per square metre means that every second 2200 Joules of energy is lost from an area measuring one metre by one metre. This happens to be is the rate at which the average human body loses heat to the surrounding air when it is -48°C with no wind blowing at all. If it is only -25°C outside but the wind is blowing at 40 km/hr., it will feel like -48C because the rate at which heat if being lost is also 2200 Watts per square metre. While -25°C is much warmer than -48°C, the wind increases the rate of heat loss. This wind-enhanced heat loss is what we call the windchill.

And more ...

When the temperature increases our bodies adapt by perspiring. Slight breezes are enough to evaporate this water from our bodies and cool us off. In effect, the heat energy within the perspiration is dissipated to the atmosphere within water vapor molecules. As the heat leaves our skin surface, there is a cooling effect. On hot, humid days, the atmosphere is more saturated with water vapor and fewer molecules are able to evaporate into the air. As a result, the cooling effect of heat loss is lessened. So, we try to find places where the air temperature is cooler (shade, air conditioning, etc.) or the breeze is greater (open areas, electric fans, etc.).