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Pressure, Altitude, and Nepal's Diversity

Using a formula to turn pressure into elevation — and what elevation means for life

Grades 9–10 45 min experiment live IESH data

Students derive the altitude of the sensor station from live barometric pressure data using the barometric formula, then explore how altitude shapes temperature, oxygen availability, biodiversity and human culture across Nepal's vertical landscape.

Learning objectives

  • Apply the barometric formula to calculate altitude from atmospheric pressure.
  • Explain why pressure decreases with altitude in terms of the weight of air.
  • Describe the relationship between altitude and temperature using the lapse rate.
  • Analyse how altitude shapes ecosystems, agriculture and human physiology in Nepal.

Background

The barometric formula describes how atmospheric pressure changes with altitude. In simplified form: Altitude (m) = 44,330 × [1 − (P/P₀)^0.1903], where P is the measured pressure and P₀ = 1,013.25 hPa is the standard sea-level reference pressure. Our sensor hub already computes this for you — but understanding the formula means understanding why the relationship works.

Pressure falls with altitude because there is simply less air above you. At sea level, the entire atmosphere presses down on you. At 5,000 m, about half the atmosphere is below you, so pressure is roughly half of sea-level pressure (about 540 hPa). At the summit of Everest (8,849 m), pressure is only about 33% of sea-level pressure — which is why supplemental oxygen is required for most climbers.

Temperature also falls with altitude — on average 6.5°C per 1,000 m, known as the environmental lapse rate. This means a location at 3,000 m will be roughly 19.5°C cooler than a location at sea level, all else being equal. Combined with lower pressure and reduced oxygen partial pressure, this makes high altitude environments profoundly different from the lowlands.

Procedure

  1. Read the current pressure value from the sensor hub: P = ___ hPa
  2. Using the formula Altitude = 44,330 × [1 − (P ÷ 1013.25)^0.1903], calculate the estimated altitude of this station. Show your working.
  3. Compare your calculated altitude with the displayed altitude on the dashboard. Are they the same? If not, why might they differ?
  4. Note the current air temperature: T = ___ °C. Using the lapse rate of 6.5°C per 1,000 m, estimate what the air temperature would be at sea level right now.
  5. Look up (or estimate) the altitude of: (a) Kathmandu (b) Lukla airport (c) Everest Base Camp (d) Namche Bazaar. Calculate the expected pressure at each location.
  6. Draw a table with columns: Location | Altitude (m) | Expected Pressure (hPa) | Expected Temp if today's sea-level temp is X°C. Fill it in for the four locations.

Discussion

  1. Water boils at 100°C at sea level. At altitude, it boils at a lower temperature. Why might this matter for cooking rice or making noodles at a high-altitude teahouse?
  2. Sherpa communities have lived at altitude for generations. What physiological adaptations would help them thrive where others struggle? How might these show up in medical measurements?
  3. A village relocates from 800 m to 2,500 m to escape flooding. What changes would the inhabitants notice in their daily lives within the first week?

Worksheet

1. Show your full calculation for the altitude of this station from today's pressure reading. P = ___ hPa. Calculated altitude = ___ m. [5 marks]

Answer guide (for teachers)

Check arithmetic. At 866 hPa, altitude ≈ 1,289 m. Accept ±50 m for rounding. Full marks for showing all steps.

2. Explain in TWO sentences why atmospheric pressure is lower at the top of a mountain than at sea level. [3 marks]

Answer guide (for teachers)

There is less air above you at higher altitude, so the total weight of the air column pressing down is less. Pressure is created by the weight of air, so less air above = lower pressure.

3. A climber at Everest Base Camp (5,364 m) has a pressure reading of approximately 505 hPa. What percentage of sea-level pressure is this? Why does this make breathing difficult? [4 marks]

Answer guide (for teachers)

505 ÷ 1013.25 × 100 = 49.8% — roughly half. This means oxygen partial pressure is also about half of sea level, so each breath delivers roughly half as much oxygen to the blood.

Vocabulary

Barometric Formula
A mathematical equation relating atmospheric pressure to altitude above sea level.
Lapse Rate
The rate at which air temperature decreases with altitude; on average 6.5°C per 1,000 m.
Hectopascal (hPa)
The unit of atmospheric pressure; 1 hPa = 100 Pascals. Standard sea-level pressure is 1,013.25 hPa.
Orographic Effect
The influence of mountains on local weather, including forced uplift of air masses and rain shadows.

Extension

Research the concept of the "Death Zone" above 8,000 m. Write a scientific explanation of why the human body cannot acclimatise above this altitude, using pressure and oxygen partial pressure in your answer.

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