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Vapor Pressure

Pressure exerted by a gas above a liquid in a sealed container

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High-Altitude Astronomy


Credit: Alan L
Source: http://www.flickr.com/photos/35188692@N00/2282306375
License: CC BY-NC 3.0

Snow in Hawaii? This island paradise is supposed to be warm and sunny all year round. And it is, except for a few isolated spots. On the Big Island, the twin mountains of Mauna Kea (13,800 feet), Mauna Loa (13,700 feet) get some snow every year. Haleakala on Maui only stands slightly above 10,000 feet and is not likely to get as much snow as the other two mountains. All three mountains have observatories located on their summits.

Why It Matters

  • The boiling point of water is affected by the atmosphere above the water. The higher the altitude, the lower the boiling point due to a decrease in vapor pressure. At the top of Mauna Kea, water will boil at approximately 186°F or 85.6°C. These decreases in boiling point temperature will lead to somewhat cooler water for making coffee or tea. Cooking will also be affected since the CO2 generated by baking soda or yeast will cause faster expansion since the pressure is lower.
  • Altitude has a significant effect upon oxygen content and utilization by the body. The fraction of oxygen in the air is essentially the same (~20%), but the amount available will be less since the air pressure is lower. Therefore, less oxygen will reach the cells to provide energy. Oxygen deprivation can begin as low as 8,000 feet for some people.
  • A high-altitude observatory presents advantages in terms of clarity of sight, less light and less air pollution. The drawback is the low oxygen concentration at high altitudes. As a result, many observatory functions are automated and monitored remotely. However, there are resident scientists and staff at the summit of Mauna Kea. These people are required to come down from the mountain every four days to reverse the effects of oxygen deprivation that leads to impaired mental functioning.
  • Credit: Matt Rafferty
    Source: http://www.flickr.com/photos/62546270@N07/6855901968/
    License: CC BY-NC 3.0

    The low light pollution at Mauna Kea allows for fantastic images of the night sky [Figure2]

  • Watch a video at the site below to see some of the observatories on Mauna Kea: https://www.youtube.com/watch?v=hRuvLgTi-ow

Can You Apply It?

Use the links below to learn more aboutthe effects of high altitude, thenanswer the following questions.

  1. What happens to liquids at high altitudes when cooking?
  2. Will dough rise faster or slower at high altitude?
  3. What is one of the first symptoms of hypoxia?
  4. Does successful acclimatization restore the same level of physical and mental functioning?
  5. What precautions are taken for staff working at Mauna Kea?

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Image Attributions

  1. [1]^ Credit: Alan L; Source: http://www.flickr.com/photos/35188692@N00/2282306375; License: CC BY-NC 3.0
  2. [2]^ Credit: Matt Rafferty; Source: http://www.flickr.com/photos/62546270@N07/6855901968/; License: CC BY-NC 3.0

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