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Aviators - Flying Doctor

From time to time, people engaging in outdoor activities may feel unwell or injure due to heatstroke, heat exhaustion or other reasons, in particular in hot weather, requiring the Government Flying Service to provide assistance. A group of voluntary flying doctors and nurses will also provide timely support and help. A new episode of "Cool Met Stuff" tells you the works of the flying doctors. (The video is broadcasted in Cantonese) For more details, please visit Hong Kong Observatory website.

Innovate with Science, Serve with Heart (Hong Kong Observatory)

The Hong Kong Observatory keeps pace with the times to provide people-oriented quality services in meteorology and related fields, and to enhance the society's capability in natural disaster prevention and response through science, innovation and partnership.MULTI-CHANNEL INFORMATION DISSEMINATION TO RAISE PUBLIC AWARENESS ON DISASTER PREVENTION With increasing demand for weather-related information, the Observatory's online information service recorded more than 146 billion page views in 2018. The total number of downloads of the "My Observatory" mobile application exceeded 7.8 million. The Observatory also provided timely weather reminders and warnings through the social media platforms such as Facebook and Instagram. Several days before Super Typhoon Mangkhut hit Hong Kong, the Observatory began to issue daily Facebook posts to alert the public to take preventive measures. Frequent updates on wind strengths and storm surges were provided on the day when the typhoon hit Hong Kong, enhancing public awareness and resilience to natural disasters.INNOVATIVE SERVICES WITH INTERDISCIPLINARY COLLABORATIONS In line with the "paperless aircraft cabin" measure, the Observatory partnered with the aviation industry to launch the "MyFlightWx" electronic flight bag mobile application, the world’s first-of-its-kind developed by an official meteorological authority. On the subject of big data analysis and smart city development, the Observatory developed “microclimate monitoring stations” to collect high-density meteorological data for studying urban climate and supporting personalised weather information services. The "SWIRLS" nowcasting system developed by the Observatory supports rainstorms forecasting and warning services operations. Such forecasts are also provided to other government departments to mitigate landslips, enhance ecology and preserve freshwater. The system has also won various information technology awards. The Observatory was designated by the World Meteorological Organisation as a Regional Specialised Meteorological Centre (RSMC) for Nowcasting in 2018. It is a recognition of the significant international role that the Observatory plays in applying nowcasting techniques.INCORPORATING OPINIONS, INNOVATING CONTINUOUSLY, KEEPING PACE WITH THE TIMES The Observatory has established sharing platforms such as Yammer and WhatsApp Group to enhance interactions and collaborations among colleagues. There are also very diverse modes of external communications, including regular liaison group meetings with the maritime, aviation and media communities to understand the needs of users and the effectiveness of service applications. The "Strategic Advisory Committee", which is composed of scholars and experts from different sectors, examines the Observatory's services from various perspectives. Members of the "Community Weather Observing Scheme" and "Friends of the Observatory" are also invited to participate in testing new products and services. Through incorporating opinions from different stakeholders, long-term development strategies and objectives are formulated so that the Observatory can continue to innovate and keep pace with the times. (The video is broadcasted in Cantonese) (For more details, please visit Sevice Excellence Website)

Scientific Assistant

A Student Scientific Assistant is mainly deployed on undertaking formal and on-the-job training for a period of two to three years in general scientific work, such as weather observing, coding and chart analysis, radioactivity monitoring, operation and calibration of scientific instruments, scientific computations, operation and utilisation of information technology systems and applications development.He/she may be required to work outdoors, shifts, outside normal office hours, or in adverse weather condition.(Note: A Student Scientific Assistant who has satisfactorily completed at least two years' training, passed a departmental examination and is considered to have fulfilled the requirements of the grade and service need may be promoted to the Scientific Assistant rank.) Organisation chartOfficial recruitment page

Radar Specialist Mechanic

A Radar Specialist Mechanic is mainly deployed on development, installation and maintenance of electronic equipment including radars, computer-based equipment and telemetry systems.Entry Requirements1) Have either a Higher Certificate in Electronic Engineering from a Hong Kong Polytechnic/polytechnic university/technical institute, or equivalent; or an appropriate certificate on maintenance of telecommunication & radar equipment from a recognized institution; and2) Have 8 years' practical experience in the development, installation and maintenance of radar, electronic or microprocessor equipment and systems; and3) Be fluent in Cantonese and spoken English; and4) Have met the language proficiency requirements of Level 2 or above in Chinese Language and English Language in the Hong Kong Diploma of Secondary Education Examination or Hong Kong Certificate of Education Examination, or equivalent. Organisation chartOfficial recruitment page

Analyst/Programmer

To meet the pace and needs for development, the Observatory also recruits Information Technology (IT) contract staff to develop software and applications related to scientific research and services. Here above the analyst programmers shared on their work and personal experience at the Observatory. Organisation chartOfficial recruitment page

Why is February shorter than other months?

Why is the number of days in February smaller than that in other months?  How were the rules for leap year established? Do you know that leap years do not always occur every 4 years? These will be explained in the episode of "Cool Met Stuff".(The video is broadcasted in Cantonese) (For more details, please click here to read the article written by Hong Kong Observatory) (Information provided by Hong Kong Observatory)

Why does food taste bland on airplanes?

People having in-flight meals always find their food not particularly tasty. Is this a result of budget consideration of the airlines or some other causes?It may be interesting to note that some physical parameters of the environment would affect our sense of tastes. According to some foreign studies, under dry and low air pressure conditions, the sensitivity of our taste buds to sweet and salty food will be reduced by 30%. Charles Spence, a professor of Experimental Psychology at Oxford University, pointed out that food and drinks taste differently in the air as compared with that on the ground. There are several reasons for this. Among them, humidity, air pressure and environmental noise each plays a role.After the plane takes off and reaches the cruising altitude (usually at about 30,000 feet high), the flight attendants will start to serve meal to the passengers. It is noteworthy that as the plane climbs, the environmental conditions like humidity and pressure in the cabin also change, and these could affect our sense of taste and smell of food.At 30,000 feet, air in the cabin becomes very dry with the humidity drops significantly to the region of 20 percent or below. Due to lack of moisture, our sense of smell reduces and this affects our judgement on food taste. At the same time, lower air pressure will also affect the sensitivity of our taste buds. As a result, our perception of saltiness and sweetness of food also drops. All these make food taste blander inside the cabin of a flying aircraft. Of course, caterers of in-flight meals would endeavour to enrich the flavour of their food served aloft in response.In the atmosphere, pressure and temperature are changing all the time. It seems like ‘magic’ to generate various kinds of weather phenomena. Be it sunny, rainy, windy, and cold or hot, they all affect our outdoor activities. In fact, changes of these physical parameters in the environment also affect humans, at indoor venues or at some dozen thousand feet above the ground. (For more details, please click here to read the article written by Hong Kong Observatory) (Information provided by Hong Kong Observatory)

Why is candlelight yellow and gas-grill light blue?

Why is candlelight yellow and gas-grill light blue? It all depends on how much oxygen is around.  Lots of oxygen makes blue flames, while limited oxygen produces yellow flames.The amount of oxygen that is available for candlelight is still not sufficient to give complete combustion, i.e. for all the wax to become water vapour and carbon dioxide.  Under the heat, some of the wax (paraffin) breaks down into tiny particles of carbon, which is called soot.  These particles are heated up under the high temperature and glow with a bright yellow light.  This makes candlelight yellow.  On their way up the flame, most of the particles find enough oxygen to burn themselves out. Some of the carbon particles, i.e. soot, do remain, however.  You can catch them by putting a knife or spoon in the flame for a few seconds.  The blade will collect a black coating of carbon the same material you find on the inside of a chimney.  Soot is a source of pollution, and is commonly found in poorly maintained vehicles and from coal-burning homes and industries.All in all, there is too much fuel and too little oxygen going on in candlelight.  This makes the combustion far from an efficient process. In contrast, a gas-grill flame is more efficient.  It uses gaseous fuel, i.e. no vapourizing is required.  The burning is almost complete and the flame is much hotter than candlelight and can reach several hundred degrees Celsius.  The fuel molecules emit blue and green light when hot.  The human eye is more sensitive to blue light, hence we perceive a blue flame. (For more details, please click here to read the article written by Hong Kong Observatory) (Information provided by Hong Kong Observatory)

Why are spectacles or camera lens so difficult to clean?

Why are spectacles or camera lens so difficult to clean? It seems to get worse when an ordinary cloth is used, which tends to produce mult-coloured marks.When an ordinary cloth is used to rub grease off the glass, the grease becomes an additional coating with varying thickness. This produces multi-coloured reflections, because light is made up of different colours (i.e. different wavelengths). The 'rainbow' effect is similar to what we see when looking at a wet road with an oil film on it.What is the proper way to clean the glasses?Use the special cloth that comes with spectacles or camera lens. It is made of thin fibres that are good at picking up grease, rather than spreading it.A wet method involves washing with soap or a little liquid detergent. Then rinse, and leave it to dry or dry with a clean linen. You can also go to an optical shop for such a service. (For more details, please click here to read the article written by Hong Kong Observatory) (Information provided by Hong Kong Observatory)

Why does wet sand look darker than dry sand?

Water is colourless and transparent, but why is wet sand darker than dry sand? Is it because water absorbs more light than air? Not entirely correct. All else being equal, wet sand looks darker because not much light is coming out. For sand grains in water, the change in the direction of light is smaller than in air. On average, it takes a much longer path for light in wet sand to come out (left) than in dry sand (right). The longer the path, the greater the chance that light gets absorbed. Hence, wet sand looks darker than dry sand. (For more details, please click here to read the article written by Hong Kong Observatory) (Information provided by Hong Kong Observatory)

Myths about protection against UV radiation

Although most people are aware of the need to take protective actions against sunburn, there are some common misconceptions about UV radiation and the ways of protection: Myth 1: Darker sunglasses offer more protection from UV radiationThe most important thing to look for in sunglasses is how much UV radiation they filter out.  It should be noted that there is no relationship between the colour of sunglasses and their UV filtering action.  When one wears sunglasses the pupil widens as there is less light reaching the eye.  If the sunglasses have poor UV protection, the amount of UV radiation getting into the eyes may even be greater than not wearing sunglasses at all.  For adequate protection, one should wear sunglasses that are able to block at least 98% of the UV radiation. Myth 2: You can't get sunburn on a cloudy dayYou do get sunburned on a cloudy day, that is of course, if you are engaged in outdoor activities but not properly protected against ultraviolet radiation (UV).  It is true that on a cloudy day, you won't get as much exposed to UV from direct sunlight as when it is a clear sunny day.  However, sunlight, including UV, are scattered by gases in the atmosphere, as well as by clouds, dust, haze and even fog. Up to 80% of solar UV radiation can penetrate thin cloud cover.  There are also occasions when broken clouds enhance UV radiation by reflection from their sides.Therefore, in case of doubt, it is advisable to check the latest UV index through radio, television, the Observatory's website and Dial-a-Weather system (1878200). Myth 3: You can't get sunburn while in the waterWater offers only minimal protection from UV radiation.  At half a metre under water, the UV radiation level is still 40% as intense as at the surface.  Also, the part of body above water is additionally exposed to ultraviolet rays reflected from the water surface. Myth 4: Sunscreen lotion protects me so I can sunbathe much longerSunscreen lotion should not be used to increase sun exposure time but to increase protection during unavoidable exposure. The protection provided by sunscreen lotion depends critically on their correct application.  For more about sunscreen lotion and sunburn protection, please check out "Sunburn and SPF". Myth 5: If you take regular breaks during sunbathing you won't get sunburnUV radiation exposure is cumulative.  The total health damage you get will be the sum of the effect of individual exposure.  Therefore, to protect yourself the objective is to reduce exposure to UV radiation as far as practicable. This could decrease the chance of skin cancer. Myth 6: If you don't feel the hot rays of the sun you won't get sunburnSunburn is caused by UV radiation which cannot be felt.  The heating effect is caused by the sun's infrared radiation and not by UV radiation.  Therefore, even if you don't feel the warmth, you may also get sunburn. Human exposure to UV radiation may result in acute and chronic health effects on the skin, eye and immune system. So please be aware to take protective actions against sunburn. (For more details, please click here to read the article written by Hong Kong Observatory) (Information provided by Hong Kong Observatory)

How does the weather affect running?

How does the weather during the day and at night affect running?  How does temperature affect relative humidity?  What things do we need to pay attention to before and after running?  Karen Cheng and Dr. Lobo H.T. Louie will explain these in this episode of "Cool Met Stuff".(The programme is broadcasted in Cantonese) (For more details, please click here to read the article written by Hong Kong Observatory) (Information provided by Hong Kong Observatory)

The physics of gurgling

What causes the bubbling sound when drinking from a bottle?When drinking from an inverted bottle, a vacuum starts to appear at the top as water flows out of the bottle. Because of the air pressure outside, air forces its way through the neck of the bottle and bubbles up. This is followed by more water escaping, and more air bubbles moving up. So on and so forth. The glug-glug is caused by these two alternating processes.Does water flow faster at the beginning or near the end?Water flows faster at the beginning because this is when the pressure is highest.Does water flow faster when the bottle is in an inverted position (i.e. upside down) or when it is tilted?(The experiment can be carried out quite easily in a kitchen or bathroom. The result accords with our experience.)Water flows faster when the bottle is tilted, i.e. at an angle. This avoids the gurgling, i.e. air bubbles coming up through the liquid, which obstructs the passage of water.What is the fastest way to pour out water?The fastest way is to pour water at an angle and with a swirl. To create a swirl, move the bottle in small circles before pouring. This way, water moves to the side of the bottle and no gurgling occurs, allowing air to freely enter through the centre (For more details, please click here to read the article written by Hong Kong Observatory) (Information provided by Hong Kong Observatory)

Why does lightning always come before thunder?

“The God of Thunder was empowered by the Jade Emperor to punish bad people on the Earth. “ “Once, the God of Thunder mistakenly killed a kind-hearted woman.  The Jade Emperor, having looked into the matter, raised the woman from death and named her the Goddess of Lightning.  He also dictated that whenever the God of Thunder stroke the Earth, he must let the Goddess of Lightning release light first to distinguish the right from wrong and prevent injustice. “ The above is just a Chinese legend. In nature, a lightning flash and the associated thunder occur at almost the same time in a thunderstorm. A person on the ground sees the lightning flash before hearing the thunder because light at a speed of around 300,000,000 meters per second travels much faster than sound which moves at 340 meters per second.  If one is 1,000 meters away from the thunderstorm, he/she would see the flash almost instantly after lightning occurs as it takes just a few microseconds, while the thunder arrives only after about 3 seconds (1,000 meters divided by 340 meters per second). As a rule of thumb, by counting the seconds between the flash and the thunder and dividing the number by 3, you can estimate your distance from the thunderstorm in kilometers.  For example, if you hear the thunder 9 seconds after seeing the flash, the thunderstorm should be about 3 kilometers away from you.  If you see a flash and hear a thunder clap almost simultaneously, the storm must be very near you. Seek shelter immediately. (For more details, please click here to read the article written by Hong Kong Observatory) (Information provided by Hong Kong Observatory)

Scientific Officer

Miss Eunice Lee, a Scientific Officer of the Hong Kong Observatory, introduces the work of a Scientific Officer.A Scientific Officer is mainly deployed on performing weather forecasting duties, supervising and training staff and carrying out research in connection with the provision of services in areas including weather, climate, seismology, radioactivity, hydrometeorology, physical oceanography, aviation meteorology, marine meteorology and applied meteorology.A Scientific Officer may be required to attend training courses locally. He/She may also be sent on an overseas course in meteorology and/or other relevant subjects. He/She may be required to work outdoors, shifts, outside normal office hours, or in adverse weather condition. Organisation chartOfficial recruitment page

Experimental Officer

Mr Ken Wong, an Experimental Officer of the Hong Kong Observatory, talks about his career as an Experimental Officer.An Experimental Officer is mainly deployed on weather forecasting, data processing, radioactivity, hydrometeorological, physical oceanographic, seismological, and time services duties.An Experimental Officer may be required to attend a professional training course in meteorology during his/her probationary period. He/She may be required to work outdoors, shifts or outside normal office hours. Organisation chartOfficial recruitment page

Why do stars twinkle?

Since no astronaut while traveling in space has reported seeing stars twinkling, the effect must be atmospheric, i.e. due to air. However, it is not exactly correct to say that it is due to turbulence in the air.Mere turbulence in the air is just what we call wind. Wind does not make stars twinkle, because light travels at a great speed --- over 1 billion km/h.What distorts the light coming from a star is temperature variations in the air. As you probably know already, air temperature varies a great deal. It typically decreases by 6.5 degrees Celsius for every kilometre you go up, and this accords with the experience that it feels cooler up in the mountains. Also, on a hot day, you may notice the shimmering waves (thermals) that come off a heated road and make a distant car appear wavy.But exactly how do temperature variations cause twinkling?When light enters a transparent medium, such as air, it generally changes direction, i.e. it is scattered. By how much it changes direction, i.e. bent, however, depends on the temperature.Now any star, except the sun, is so far away that practically, it is sending only a single ray of light towards us. As that ray enters the atmosphere, it is scattered differently as it passes through air of different temperatures. When it is scattered away from us, the star seems to disappear for a moment. When it is scattered into our eyes, it seems to reappear, resulting in a twinkle.For more details, please click here to read the article written by Hong Kong Observatory. (Information provided by Hong Kong Observatory)

Why "a few degrees lower over the New Territories" often appears in the weather forecasts?

The phrase "a few degrees lower over the New Territories" often appears in the weather forecasts during autumn and winter, in order to remind the public of the temperature difference between different regions. This episode of "Cool Met Stuff" will briefly explain the cause of this phenomenon in the form of a playlet.    (Information provided by Hong Kong Observatory)