The class starts off with a demonstration of calculating the relative humidity, heat index, and risk level for activity using a wet and dry bulb thermometer. Tables based in part on the heat index calculator.
Other weather calculators.
Web bulb depression in °C: Dry bulb minus the wet bulb | |||||||
---|---|---|---|---|---|---|---|
Dry bulb T in °C | 0.5 | 1.0 | 2.0 | 2.5 | 3.0 | 3.5 | 4.0 |
21 | 95% | 90% | 83% | 79% | 77% | 72% | 67% |
24 | 96% | 91% | 84% | 80% | 78% | 74% | 69% |
27 | 96% | 91% | 85% | 81% | 78% | 75% | 71% |
28 | 96% | 93% | 85% | 82% | 78% | 75% | 72% |
29 | 96% | 93% | 88% | 84% | 80% | 76% | 73% |
30 | 96% | 93% | 86% | 82% | 79% | 76% | 73% |
32 | 96% | 93% | 89% | 85% | 81% | 78% | 74% |
35 | 96% | 93% | 89% | 85% | 82% | 79% | 75% |
38 | 96% | 93% | 89% | 86% | 83% | 80% | 76% |
Dry bulb temperature in °C | |||||||||
---|---|---|---|---|---|---|---|---|---|
Relative humidity | 21 | 24 | 27 | 28 | 29 | 30 | 31 | 32 | 35 |
60% | 21 | 24 | 28 | 29.5 | 32 | 33 | 35 | 38 | 46 |
70% | 21 | 25 | 29 | 30.7 | 34 | 35 | 37 | 41 | 51 |
80% | 22 | 26 | 30 | 32.1 | 36 | 38 | 40 | 45 | 58 |
90% | 22 | 26 | 31 | 33.7 | 39 | 41 | 43 | 50 | 64 |
100% | 22 | 27 | 33 | 35.6 | 42 | 44 | 49 | 54 | 72 |
Effective temperature in °C: | Risk level |
---|---|
Less than 32 °C | Low risk: Safe to exercise with proper hydration |
32 °C to 41 °C | Moderate risk: Heat cramps or heat exhaustion likely |
Above 41 °C | High risk: Heat stroke likely. |
Discuss the implications for runners and other athletes in Micronesia
Warm air rises (convection) and cools. Cooler air holds less water than warmer air. The result is that water condenses out of the air as the air rises. This condensation is visible as clouds. Condensation requires dust, smoke, or other microscopic airborne particles for the water to condense upon. As a result of this condensation, precipitation can occur. Precipitation is produced by three different processes, although the first process is dominant in Micronesia.
Other notes
Types of Precipitation
Rain, snow, sleet, hail, dew (radiative cooling), or fog. Radiation fog.
Supercooled water, ice necessary to lightning, thunder. Distance versus time. 330 m/s, about three seconds per kilometer. So divide by three to get distance in kilometers. No shelter under trees! Squat. Stay in car.
Air masses:
Two. Maritime equatorial mE air mass ("doldrums" for lack of wind) most of the year. Jan-Feb ("trade wind season") maritime tropical mT air mass.
No warm and cold fronts. Pressure waves along the equator, local heating effects.
InterTropical Convergence Zone: ITCZ
Tropical storms
Areas of organized convection
Tropical depression (Get numbered!)
Requirements: SST > 28 C, low vertical shear, high pressure anti-cyclone aloft
CATEGORY | DESCRIPTION | MAX SUSTAINED WINDS | PEAK GUSTS |
---|---|---|---|
TROPICAL DEPRESSION AND TROPICAL STORM CATEGORIES | |||
Tropical Storm Category A | Weak Tropical Storm | 26-43 knots (30-49 mph) | 33-56 knots (40-64 mph) |
Tropical Storm Category B | Severe Tropical Storm | 44-63 knots (50-73 mph) | 57-81 knots (65-94 mph) |
TYPHOON and SUPERTYPHOON CATEGORIES | |||
Typhoon Category 1 | Minimal Typhoon | 64-82 knots (74-95 mph) | 82-105 knots (95-120 mph) |
Typhoon Category 2 | Moderate Typhoon | 83-96 knots (96-110 mph) | 106-121 knots (121-139 mph) |
Typhoon Category 3 | Strong Typhoon | 97-113 knots (111-130 mph) | 122-144 knots (140-165 mph) |
Typhoon Category 4 | Very Strong Typhoon | 114-134 knots (131-155 mph) | 145-171 knots (166-197 mph) |
Typhoon Category 5 | Devastating Typhoon | 135-170 knots (156-194 mph) | 172-216 knots (198-246 mph) |
El Niño (and La Niña)
Westerly wind burst
Surface layers slide west
Convection moves west