Bureau of Meteorology
X

About

The BOM Blog gives you the background and insider info on weather, climate, oceans, water and space weather—as well as the latest on the work of the Bureau.

Comments

We welcome participation in the comments section of our blog; however, we are not able to respond to all comments and questions and your comments may take a little time to appear. The blog is monitored from 9 am to 5 pm Monday–Friday.

Our community includes people of all ages and backgrounds and we want this to be a safe and respectful environment for all. To keep the discussion interesting and relevant, please:

  • respect other people and their opinions;
  • keep your comments on topic and succinct;
  • say why you disagree or agree with someone;
  • comment constructively—in a way that adds value to the discussion.

When commenting, please don't:

  • make defamatory, libellous, false or misleading comments;
  • use obscene, insulting, racist, sexist or otherwise discriminatory or offensive language;
  • post personal information about yourself or others, such as private addresses or phone numbers;
  • promote commercial interests;
  • violate the intellectual property rights of others;
  • violate any laws or regulations;
  • provoke others, distort facts or misrepresent the views of others; or
  • post multiple versions of the same view or make excessive postings on a particular issue.

We won’t publish comments that are not in line with these standards. Blocking/removal of content or banning of users is at our discretion.

There is no endorsement, implied or otherwise, by the Bureau of any material in the comments section. Users are fully responsible for the content they submit.

Commenting is available via a Facebook plugin, which can only be accessed by those with Facebook accounts.

You can contact us at socialmedia@bom.gov.au.

Copyright | Disclaimer | Privacy

X

Contact our social media team at socialmedia@bom.gov.au

Ask BOM: How is temperature measured?

Ask BOM: How is temperature measured?

To take temperature measurements, thermometers are placed inside instrument enclosures known as a Stevenson screen.


A Stevenson screen is basically a box with louvres that allow air to circulate around the thermometer inside while protecting it from outside elements like rain and direct sunlight. The outside is painted white to minimise heat absorption. This basic design has been around for about 150 years, and is used by most meteorological organisations around the world.

Choosing the right position for a Stevenson screen is really important. Nearby objects like buildings and trees can reflect or absorb heat, so the Bureau always tries to place a Stevenson screen well away from any such features. We always set the screens up over a natural surface, like grass, and avoid surfaces like concrete.

The screen is raised so that the thermometer is 1.2 m above the surface, because there can be as much as a 7°C temperature difference between the temperature measured at the ground and 2 m above the ground. In the southern hemisphere we face the screen to the south, so that even when the door is open we avoid direct sunlight hitting the thermometer.

A Stevenson screen, closed (left) and open (right), containing a resistance temperature device (thermometer) and a relative humidity probe
A Stevenson screen, closed (left) and open (right), containing a resistance temperature device (thermometer) and a relative humidity probe.

Traditionally, trained observers would read the thermometer and send in the observations at least twice a day—normally at 9 am and 3 pm; but these days we have automatic thermometers that send in the information electronically, so the Bureau can collect a lot more data.

The Bureau has been measuring air temperature for over 100 years now, and we have around 700 automatic weather stations set up all over the country, so Stevenson screens are important for getting consistent air temperature measurements—no matter where you are.

Comment. Tell us what you think of this article.

Share. Tell others.