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The Monsoon in Numbers

How Nepal's defining weather pattern shows up in sensor data

Grades 8–10 45 min analysis live IESH data

Students analyse temperature and humidity data from the dashboard, identify the signature of Nepal's monsoon season, and explore how this single weather pattern shapes agriculture, festivals, disasters and daily life.

Learning objectives

  • Read a time-series graph and identify trends, peaks and troughs.
  • Calculate the mean temperature and mean humidity from a data set.
  • Explain the mechanism driving Nepal's monsoon using temperature and pressure concepts.
  • Evaluate the social and economic consequences of monsoon variability for Nepal.

Background

The monsoon is not simply a rain season — it is a large-scale reversal of wind direction driven by differential heating. In summer, the land mass of South Asia heats up far more quickly than the Indian Ocean. Hot land creates low pressure over the continent; the relatively cooler ocean maintains higher pressure. Air flows from high pressure to low, bringing moisture-laden ocean air northward and inland. As this air rises over the Himalayas and cools, it releases its moisture as rain — sometimes over 200 mm in a single day in the hills.

On a sensor, the monsoon arrival shows up clearly: humidity rises sharply from below 50% to consistently above 75%, temperatures may dip slightly as cloud cover reduces solar heating, and pressure often fluctuates with passing storm systems. After the monsoon withdraws in October, humidity drops, skies clear, and the sensor records Nepal's famously pleasant autumn weather.

The relationship between the monsoon and Nepali society is deep. The rice planting calendar is set by monsoon onset. The festival of Ropain (paddy transplanting) is a community celebration tied directly to soil moisture reaching planting conditions. Water mills, irrigation canals and the entire architecture of hill agriculture are designed around the monsoon's rhythm.

Procedure

  1. Open the dashboard temperature and humidity history charts. What season are we currently in?
  2. Record the last 10 data points for temperature and humidity in a table.
  3. Calculate the mean (average) temperature and mean humidity from your 10 readings.
  4. Sketch a line graph of humidity over the 10 time points. Label the axes.
  5. In small groups, discuss: based on these readings, is this station currently in monsoon conditions? List three pieces of evidence from the data.
  6. Read the Nepal context above. List THREE ways the monsoon arrival matters to a Nepali farmer in the hills.
  7. Write a paragraph predicting what the humidity graph would look like from June to November.

Discussion

  1. Why might a delayed monsoon be economically devastating for a farming family in Sindhupalchok?
  2. Climate change is predicted to make monsoon rainfall more intense but less predictable. What does "more intense but less predictable" mean for farmers?
  3. Can you think of a festival or cultural practice in your own community that is tied to the seasons or weather?

Worksheet

1. From your 10 data points, calculate: Mean temperature = ___ °C Mean humidity = ___ % Show your working. [4 marks]

Answer guide (for teachers)

Check arithmetic. Students should sum values and divide by 10.

2. Describe what happens to temperature and humidity in Nepal as the monsoon arrives in June. Use the words "increases", "decreases" and "because". [4 marks]

Answer guide (for teachers)

Humidity increases significantly because moisture-laden air arrives from the Bay of Bengal. Temperature may decrease slightly or remain similar because cloud cover reduces direct solar heating, but feels hotter due to high humidity.

3. Why does Nepal receive so much more monsoon rain than a country at the same latitude in, say, North Africa? [4 marks]

Answer guide (for teachers)

Nepal is directly in the path of the South Asian monsoon driven by the Indian Ocean. The Himalayas force moist air upward (orographic lift), causing heavy rainfall. North Africa is shielded from ocean moisture by distance and atmospheric circulation patterns.

4. Suggest ONE way a farmer could use a weather sensor like this one to make better farming decisions. [2 marks]

Answer guide (for teachers)

Accept reasonable answers: tracking soil drying after monsoon, deciding when to plant, monitoring temperature for frost risk at high altitude, identifying unusual drought conditions early.

Vocabulary

Monsoon
A seasonal wind system that reverses direction between summer and winter, bringing wet summers to South Asia.
Orographic Rainfall
Rain caused when moist air is forced upward by mountains, cooling and releasing its moisture.
Mean (Average)
The sum of all values in a data set divided by the number of values.
Time Series
A sequence of data points recorded at successive points in time.

Extension

Find a news article about a monsoon-related flood or drought event in Nepal in the last five years. Write a half-page analysis of how better sensor data networks across Nepal might have helped communities prepare for or respond to the event.

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