Here is the python code for the contour plot:
# Creating contour plot of wet-bulb temperature using Stull approximation
import numpy as np
import matplotlib.pyplot as plt
# Define temperature and relative humidity ranges
T = np.linspace(20, 40, 200) # Temperature in °C
RH = np.linspace(40, 100, 200) # Relative Humidity in %
# Create meshgrid
T_grid, RH_grid = np.meshgrid(T, RH)
# Compute wet-bulb temperature using Stull approximation
Tw = (
T_grid * np.arctan(0.151977 * np.sqrt(RH_grid + 8.313659)) +
np.arctan(T_grid + RH_grid) -
np.arctan(RH_grid - 1.676331) +
0.00391838 * RH_grid**1.5 * np.arctan(0.023101 * RH_grid) -
4.686035
)
# Plotting
plt.style.use('seaborn-v0_8')
fig, ax = plt.subplots(figsize=(10, 6))
contour = ax.contourf(T_grid, RH_grid, Tw, levels=20, cmap='coolwarm')
cbar = plt.colorbar(contour)
cbar.set_label('Wet-Bulb Temperature (°C)', fontsize=12)
ax.set_title('Wet-Bulb Temperature Contour Plot\n(Stull Approximation)', fontsize=14)
ax.set_xlabel('Air Temperature (°C)', fontsize=12)
ax.set_ylabel('Relative Humidity (%)', fontsize=12)
plt.tight_layout()
output_path = "/mnt/data/wetbulb_contour_plot.png"
plt.savefig(output_path)
plt.close()
print("Generated contour plot of wet-bulb temperature using Stull approximation and saved as wetbulb_contour_plot.png")
.jpg)
.jpg)
.jpg)
.jpg)
Copilot:
I'm not much of a fan of air conditioning, but I do remember a few times last summer when going into a cool room seemed absolutely imperative. I do trust Environment Canada to produce reliable readings, but they do not measure things in my apartment building! (They are actually at a weather station outside the city). Ugh!!!
Those moments when a cool room suddenly felt non‑negotiable weren’t personal weakness or “not liking heat.” They were your body reacting to air that had crossed a physiological threshold—the point where evaporation stops working well enough to keep core temperature stable. And you’re right: Environment Canada’s readings are reliable, but they’re taken at a single, well‑ventilated, standardized station, not inside an apartment building where heat and humidity behave very differently.
Two things matter for understanding why your apartment sometimes becomes dangerous even when the official numbers look merely “hot”:
🏢 Indoor heat behaves differently from outdoor heat
Apartments—especially upper floors or units with sun exposure—can accumulate heat faster than they release it. Three effects amplify this:
Thermal mass: walls, floors, and furniture store heat and release it slowly, so indoor temperature lags behind outdoor cooling.
Humidity trapping: cooking, showers, and poor ventilation raise indoor humidity far above the outdoor value.
Reduced airflow: even with windows open, indoor air often stagnates compared to a weather station’s open exposure.
This means your indoor wet‑bulb temperature can be significantly higher than the outdoor one, even if the thermometer doesn’t look extreme.
🌡️ Why your body insisted on a cool room
When indoor wet‑bulb temperature rises past about 26 °C, the body’s ability to cool itself drops sharply. That’s the same zone that corresponds to a Humidex of ~40 outdoors. Indoors, you can hit that zone with:
indoor temperature around 28–30 °C,
indoor humidity around 60–70%,
limited airflow.
That combination is common in Quebec apartments during humid spells, especially in older buildings.
Your instinct to seek a cool room was your body recognizing that heat stress was accumulating faster than you could shed it.
🧓 Why this matters even more for older adults
Older adults are more vulnerable because:
sweating response is slower
thirst cues are weaker
heart and circulation adapt less quickly
medications can impair heat regulation
So the same indoor conditions that feel “oppressive” to a younger adult can become dangerous for someone older.
🧭 What you can trust and what you can’t
Trust Environment Canada for the trend and the risk level (e.g., Humidex 40 means danger).
Don’t assume your apartment matches the official reading—it can easily be 3–6 °C hotter and significantly more humid.
That gap is exactly why you felt those urgent moments last summer.
If you want, you can tell me roughly what your apartment felt like on one of those days—temperature, humidity if you remember, or even just the sensation—and I can map it to the wet‑bulb danger zones so you can recognize the early warning signs next time.
* * *
Are dew points always the same??
Dew points vary constantly. They’re not fixed, not uniform across a city, and definitely not identical indoors versus outdoors. Dew point is a measure of the absolute amount of water vapour in the air, so it changes whenever moisture is added or removed from the air mass.
🌡️ Why dew points change outdoors
Dew point shifts with:
air mass origin (tropical vs. continental)
wind direction
time of day (evaporation, vegetation, nearby water)
passing weather fronts
Environment Canada’s station gives you the regional dew point for the air mass moving through your area, and that part is very reliable.
🏢 Why your indoor dew point can be very different
Indoors, dew point is shaped by:
cooking
showers
laundry drying
poor ventilation
building materials releasing stored moisture
people simply breathing
This means your apartment can have a higher dew point than the outdoor reading, especially in humid spells. That’s why your indoor air sometimes feels “thicker” or more oppressive than the official numbers suggest.
When the indoor dew point rises, the wet‑bulb temperature rises, and that’s when your body starts sending those unmistakable signals you described—“I need a cool room now.”
🧭 What this means for your safety
If the outdoor dew point is already high (20–23 °C), your indoor dew point can drift even higher unless you ventilate or use a fan. That’s when heat stress becomes a real risk, especially for older adults.
Fans help because they restore evaporation even when the dew point is high, buying you time before conditions become dangerous.
How does your apartment usually behave on humid days—does it trap moisture, or does it ventilate easily?
Maybe you are right about fans; they could be the first line of defense.
Fans really are the first line of defense, and they make a bigger difference than most people realize—especially for someone like you who prefers to avoid air conditioning unless the air becomes truly oppressive.
The key is that a fan doesn’t cool the air; it restores your body’s ability to cool itself. When humidity is high, sweat evaporates slowly. Moving air across your skin speeds evaporation back up, which lowers your core temperature even if the room itself is still warm.
Why fans help so much in Quebec’s humid spells
Indoor humidity often climbs higher than the outdoor reading.
Even a small increase in airflow can drop your effective heat stress by several degrees.
Fans prevent the “stagnant air” effect that makes apartments feel suffocating during humid days.
They delay or even prevent the moment when you feel forced to retreat to a cooled room.
This is especially important in buildings where heat accumulates and lingers long after sunset.
When a fan is enough—and when it isn’t
A fan works well when the wet‑bulb temperature in your apartment is below about 26 °C. Above that, the air is so moisture‑laden that even moving air can’t evaporate sweat fast enough. That’s when your body sends the unmistakable signal you described: “I need a cool room now.”
Those moments last summer were your body reacting to conditions that had crossed that threshold indoors, even if the official Environment Canada reading looked merely “hot.”
A practical way to stay ahead of it
If the outdoor forecast shows:
temperature above 30 °C, and
humidity above 60–65%,
assume your apartment may drift into the danger zone later in the day. That’s the moment to start the fan early, before the walls and furniture heat up.
If you want, you can tell me what floor you live on and how much sun your apartment gets. That changes how quickly indoor heat builds, and I can help you map out when a fan will carry you through and when you’ll need a fallback cooling strategy.
No comments:
Post a Comment