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1.Humidity and the comfort index
Beijing is controlled by the Pacific Sub-tropical high
in summer most of the time. The predominant wind direction is
south. The annual maximum humidity arrives in the first 10
days of August and the 10-day mean is 79%. Then, it decreases
gradually. By the last 10 days, it becomes 74%. In the first
10 days of September the humidity is 72%, drops to 64% by the
last 10 days. It is noticeable that the decreasing rate of
humidity in September is bigger than that in August. People do
not feel muggy in September.
Humidity has a major play
in the environment causing different responses of the human
body. High temperature and humidity make people feel muggy and
uncomfortable. Breeze cools off the environment. The thermal
comfort index calculated through the formula which is composed
of the elements: temperature, humidity and wind speed is
categorized into different levels to indicate equivalent
comfort levels (see table 1).
According to statistics,
the daytime thermal comfort index during the Olympics is
basically between 70 and 80, may reach or over 80 (level 7)
during a short period after noon. In 22.9 days in August
during the Olympics, the thermal comfort index is between 5
and 6 (hot-hotter), with an occurring probability of 74%; 0.6
day will be hot and humid, occurring probability of 2%; while
the rest 24% will be comfortable and cool (see table 2).
During the Paralympics (September), the thermal comfort index
is below 70, in which the first 10 days 67, the mid 10 days
63, and the last 10 days lower than 60 when the chill is felt.
Table 1 Criteria for Thermal
Comfort Index |
| Index |
57 |
57-60 |
60-65 |
65-70 |
70-76 |
76-80 |
80-83 |
83-85 |
85 |
| Level |
Level1 |
Level 2 |
Level 3 |
Level4 |
Level 5 |
Level6 |
Level 7 |
Level 8 |
Level 9 |
| Sense |
chill |
cooler |
cool |
comfortable |
hot |
hotter |
sultry |
sweltering |
scorching |
| Table 2 Days of Occurrence
and Probability |
| Level |
2(cooler) |
3（cool ） |
4（comfortable ） |
5（hot ） |
6（hotter ） |
7(sultry ) |
| Average
days |
0.1 |
1.1 |
6.3 |
17.6 |
5.3 |
0.6 |
| Probability（%） |
0 |
4 |
20 |
57 |
17 |
2 |
2.Solar radiation
In the spectrum of the solar radiation, the
ultra violet radiation, of which the wavelength is less than
0.4µ（400nm）, has an important and complex impact on humans.
Small amounts of UV contributes to the conversion of
cholesterin to vitamin D, hence, helps the absorption of
calcium. It can also help heal up the scar; improve the immune
system, etc. But prolonged human exposure to solar UV
radiation may result in acute and chronic health effects on
the skin, eye and immune system, even cancer.
Five Exposure Categories for UV，See table 3.：
Table3 UV Intensity, UV Index, and
Safety Actions |
| UV Intensity |
UV Index |
Safety Actions |
| Low |
0、1、2 |
Not necessary to take
special actions |
| Moderate |
3～5 |
Should take some
precaution actions, e.g. apply some sunscreen. |
| High |
6～7 |
| Very high |
8～10 |
Avoid outdoor
activities at noon time; otherwise, take proper
protective measures, such as wearing a hat and
sunglasses. Apply spectrum SPF15+ sunscreen |
| Extreme |
Above11 |
Normally,
the UV intensity before 7 am and after 5 pm in August in
Beijing belongs to category “low”; between 7 and 8 am, 3 and 5
pm, it belongs to “moderate”; rom 10 am to 1 pm, “very high”. .
Beijing locates in a low altitude area; seldom can we see
“very high”. The variation in September is similar to the
daily changes in August, but the atmospheric transparency is
better than that in August, so the UV index between 10 am and
1 pm is higher than that in August.
3.The Impact of severe weather on
sports
All the outdoor sport games are
influenced by meteorological conditions such as high
temperature, high humidity, etc. Sometimes, severe weather
like thunderstorm, hail even brings hazards or death to
people. Torrential rain may make the goal vague and reduce the
visibility, thus hinder shooting and archery competition. If
the rainfall submerges the court and makes it slippery and
consequently dangerous for the track and equestrian, the race
may be postponed or even cancelled.
During the Olympic
Games, Beijing may probably see some high impact weather
conditions like high temperature, high humidity, heavy fog,
thunderstorm, high wind and torrential rain. Statistics from
1971-2006 revealed that during the Olympic Games the rainfall
probability is 37%, a rainfall in 3 days on average. The
probability for torrential rain is only 2%. The probability
for 35oC or higher temperature, high wind, and hail is less
than 1%. IIt’s rare to see fog, radiation fog sometimes but it
will disappear soon after the sunrise. There is a thunderstorm
weather in 4 days on average, with a probability of 23.5％.
. See
the table below.
During the Paralympic Games, weather
with 35oC or above high temperature may not occur. On average,
the rainfall happens every 4 days, with the probability down
to 24％. The probability of torrential rain is nearly 0, and
very little for high wind and fog. As for thunderstorm, the
probability drops to 12.5％，we should still be on guard. See
the table below.
Table4 for Probability for High Impact
Weather Events |
| Weather Phenomena |
Probability during the Olympic Games
(%) |
Probability during the Paralympics (%) |
| Rain |
36.6 |
24.3 |
| Torrential rain |
2.1 |
0 |
| High temperature |
0.1 |
0 |
| High wind |
0.1 |
0.7 |
| Heavy fog |
6.1 |
5.8 |
| Thunderstorm |
23.5 |
12.5 |
| Hail |
0.3 |
0 |
4.Weather condition on the day of
the opening and closing ceremony of the Olympic Games
August 8, the day of the opening ceremony of the
Olympic Games, falls into the period of abundant rainfall and
high humidity in Beijing. The average day temperature is
25.6oC average day high is 30.3oC average day low is 21.7 oC day
difference in temperature is 8.6 oC But the extreme high is
34.0 oC, extreme low is 17.7 oC The rainfall probability is 47%
(see the table below).At that time, the BOCOG will operate the
emergency responding action to guarantee the games to be held
as scheduled.
Table5
Meteorological Data on the Day of Opening/Closing
Ceremony of
the Olympic/ Paralympic Games（Year 1971～2006） |
| |
Olympic Games |
Paralympic Games |
| |
Opening Ceremony |
Closing Ceremony |
Opening Ceremony |
Closing Ceremony |
| |
Aug8 |
Aug. 24 |
Sept. 6 |
Sept. 17 |
| Average Temp. |
25.6 |
24.5 |
22.1 |
19.9 |
| Average HighoC |
30.3 |
29.4 |
27.6 |
25.6 |
| Extreme HighoC |
34.0 |
33.4 |
32.3 |
34.4 |
| Average LowoC |
21.7 |
20.1 |
17.1 |
14.9 |
| Extreme LowoC |
17.7 |
15.6 |
13.1 |
5.5 |
| Rainfall
probability % |
47.2 |
25.0 |
25.0 |
27.8 |
| Relative
Humidity % |
78 |
76 |
68 |
68 |
| Average Wind
Speed m/s |
1.7 |
1.6 |
2.1 |
2.2 |
| Predominant Wind
Direction |
NNE |
S |
NNE |
SSW |
On August 24, the day of the
closing ceremony of the Olympic Games, the average temperature
is 24.5oC average high is 29.4oC . Both drop about 1oC . The
extreme high falls to 33.4oC , and the relative humidity falls
from 78%to76%
. On the day of the closing ceremony, the
probability for high temperature is rather low, while the
rainfall probability drops to 25%. It is comfortable.
During September 6 to 17 of the Paralympic Games,
Beijing has entered autumn season. The average temperature
drops to 22~20oC , average high drops to 27.6oC ~ 5.6oC . The extreme
high on the opening and closing ceremony is respectively
32.3oC and 34.4oC .It shows on the day of the opening and closing
ceremony the temperature of 30oC is possible, but the humidity
drops about 10%
. There will not be any sultry weather.
5.Weather condition along the
Marathon route
Women’s and men’s Marathon will be held on August 16 and 24 respectively. The starting line is at the grand Tiananmen Square, along the route, you can see the Temple of Heaven, the Yongding Gate, the People’s Hall, the Capital Stadium, the National Library, the People’s University, Zhongguancun Science-Technology Garden, the Peking University, Tsinghua University, the Yuan Dynasty Capital Site Garden, and the finishing line is at the National Stadium in the Olympic Garden.
The latitude difference between the starting line and the finishing line is only 8 meters. The direct line between the two points is only 9.2 km. In order to let the athletes have a better understanding of the weather conditions, we choose 7 auto-weather stations for observation of temperature, humidity, and wind; they are the stations at the Temple of Heaven (1), the Ancient Observatory (2), Guanyuan (3), Zizhuyuan (4), the College Students’ Gymnasium (5), the Olympic Center (6), and the Olympic Park (7).
As it is the mid summer during the Olympic Games，at around noon time, the temperature is high with an average about 30oC, relative humidity about 55%. The thunder shower probability is higher at dusk time. Soon after the sunrise, at 7 o’clock, the UV intensity is moderate, the temperature is around 22oC, and relative humidity is around 80%. It’s relatively comfortable. That’s why we choose 7 o’clock for the start of the competition.
Table 1 and Table 2 shows the data between 7 and 10 o’clock on the day of the Marathon race from the 7 auto-weather stations. We can see NO. 5, the College Students’ Gymnasium, has a higher temperature than the other places which means during the 36 to 37 km the temperature is higher and the humidity is lower. At the finishing line--the National Stadium in the Olympic Park, the temperature is lower. During the 2-3 hour race, the temperature is between 22 and 27 oC. The humidity varies between 80－65％. There won’t be high impact weather like thunderstorm, high wind in the morning during the race. The weather is advantageous for the normal play of the athletes.
Table 6 Weather Data on the Day of the Women’s Marathon Race |
No. of the Auto-weather
Station |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
| Average Daytime Temperature（oC） |
23.6 |
24.4 |
24.4 |
23.9 |
24.5 |
24.3 |
23.3 |
| Average Daytime High（oC） |
29.1 |
29.5 |
29.0 |
29.1 |
29.5 |
29.5 |
28.6 |
| Average Daytime Low（oC） |
19.0 |
20.4 |
20.4 |
19.9 |
20.5 |
20.1 |
19.5 |
| Average Daytime Humidity（%） |
72 |
－ |
－ |
－ |
66 |
－ |
80 |
| Average Daytime Wind Spd（m/s） |
0.7 |
1.6 |
0.8 |
0.9 |
1.4 |
1.0 |
1.1 |
| Average Daytime Wind Spd（m/s） |
11.1 |
11.3 |
11.7 |
14.3 |
7.0 |
3.5 |
6.0 |
Table 7 Weather Data on the Day of the Men’s Marathon Race |
No. of the Auto-weather
Station |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
| Average Daytime Temperature（oC） |
24.6 |
25.8 |
25.5 |
25.4 |
26.2 |
25.8 |
24.1 |
| Average Daytime High（oC） |
30.8 |
30.9 |
30.5 |
30.9 |
30.9 |
31.4 |
29.6 |
| Average Daytime Low（oC） |
19.7 |
21.9 |
21.9 |
21.3 |
22.2 |
21.5 |
19.5 |
| Average Daytime Humidity（oC） |
73 |
－ |
－ |
－ |
65 |
－ |
75 |
| Average Daytime Wind Spd（oC） |
0.4 |
1.3 |
0.6 |
0.5 |
1.0 |
1.1 |
0.9 |
| Average Daytime Max Wind （oC） |
5.6 |
4.6 |
6.5 |
7.8 |
2.9 |
3.9 |
2.4 |
Fig.1 Hourly Temp Variation
along the Marathon Route |
Fig. 2 Hourly Humidity
Variation along the Marathon Route |
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