Wet-Bulb Temperature

18 Apr 2025

Wet-Bulb Temperature

Recently, Harvard researchers suggest that the human survival limit for wet-bulb temperature may be closer to 31°C instead of the widely accepted 35°C.

  • The 35°C limit was based on a 2010 study by Sherwood and Huber, predicting heat stroke within 6 hours of exposure.
  • New physiological studies indicate severe health risks may begin at 31°C, not 35°C.

About Wet-Bulb Temperature (WBT)

  • Definition: WBT is the lowest temperature that can be achieved through evaporation at constant pressure.
  • Measurement Method: Measured by wrapping a wet cloth around a thermometer bulb; evaporation cools the bulb to show WBT.
  • Significance: It  reflects how well the body can cool via sweating which is crucial for assessing heat danger.
  • Humidity Relation: At 100% humidity, WBT equals air temperature; at lower humidity, WBT is always lower.
  • IMD Gap: The India Meteorological Department does not factor in WBT in heatwave definitions.

Wet Bulb Temperature, Dry Bulb Temperature and Dew Point

Aspect Dry Bulb Temperature (Tdb) Wet Bulb Temperature (Twb) Dew Point Temperature (Tdp)
Definition Ambient air temperature measured without moisture influence Temperature of adiabatic saturation using a moistened thermometer Temperature at which air becomes fully saturated and water vapor condenses
Measurement Method Standard thermometer shielded from moisture and radiation Thermometer bulb wrapped in wet cloth, exposed to air flow Ice-water method in a metal can or using a hygrometer
Relation to Humidity Unaffected by humidity Affected by humidity; lower Twb means lower humidity Closer Tdp to Tdb means higher humidity
Values Compared to Others Always higher than or equal to Twb and Tdp Always lower than Tdb unless RH = 100% Always ≤ Tdb; equal when RH is 100%
Psychrometric Chart Appears as vertical lines (x-axis) Appears as diagonal lines (upper-left to lower-right) Lies on the saturation curve (leftmost edge)
Applications Used to describe sensible heat or air temperature Helps estimate relative humidity and comfort level Indicates dew formation, humidity levels, and condensation risk

Archive Calendar

Mon Tue Wed Thu Fri Sat Sun
 123
45678910
11121314151617
18192021222324
25262728293031

Need help preparing for UPSC or State PSCs?

Connect with our experts to get free counselling & start preparing

Know about Physics Wallah

Physics Wallah is an Indian online education platform, that provides accessible & comprehensive learning experiences to students of classes 6 to 12 and those preparing for JEE and NEET exams. We also provide extensive NCERT solutions, sample papers, NEET, JEE Mains, BITSAT previous year papers, which makes us a one-stop solution for all resources. Physics Wallah also caters to over 3.5 million registered students and over 78 lakh+ Youtube subscribers with 4.8 rating on its app.

We Stand Out because

We successfully provide students with intensive courses by India's qualified & experienced faculties. PW strives to make the learning experience comprehensive and accessible for students of all sections of society. We believe in empowering every single student who couldn't dream of a good career in engineering and medical field earlier.

Our Key Focus Areas

Physics Wallah’s main focus is to create accessible learning experiences for students all over India. With courses like Lakshya, Udaan, Arjuna & many others, we have been able to provide a ready solution for lakhs of aspirants. From providing Chemistry, Maths, Physics formulae to giving e-books of eminent authors, PW aims to provide reliable solutions for student prep.

What Makes Us Different

Physics Wallah strives to develop a comprehensive pedagogical structure for students, where they get a state-of-the-art learning experience with study material and resources. Apart from catering students preparing for JEE Mains and NEET, PW also provides study material for each state board like Uttar Pradesh, Bihar, and others.

Aiming for UPSC?

Download Our App

# #
Quick Revise Now !
AVAILABLE FOR DOWNLOAD SOON
UDAAN PRELIMS WALLAH
Comprehensive coverage with a concise format
Integration of PYQ within the booklet
Designed as per recent trends of Prelims questions
हिंदी में भी उपलब्ध
Quick Revise Now !
UDAAN PRELIMS WALLAH
Comprehensive coverage with a concise format
Integration of PYQ within the booklet
Designed as per recent trends of Prelims questions
हिंदी में भी उपलब्ध

<div class="new-fform">






    </div>

    Subscribe our Newsletter
    Sign up now for our exclusive newsletter and be the first to know about our latest Initiatives, Quality Content, and much more.
    *Promise! We won't spam you.
    Yes! I want to Subscribe.