Author Archives: christy lau

Will it be a snow day tomorrow?

As many students frantically refreshed the UBC website to see if classes (especially midterms) were cancelled due to the recent snow storms, it became apparent the importance of accurate and early weather forecasting systems. In both Eastern Canada and Vancouver, the powerful winter wind, snow, and freezing temperatures caused power outages, road delays, and many flight cancellations. Many emergency centres and snow action plans were in operation, even before the storm hit. The science used in weather forecasting needs to predict accurately and in advance, so that weather warnings can be communicated to the government and to the public efficiently. Without this technology, millions of dollars of damage can be done and public safety could be put at risk.

The January 2019 Snow Storm in Toronto, Ontario. Wikimedia Commons

A recent published study by Fuqing Zhang in the JAS (Journal of the Atmospheric Sciences) suggests that a 2-week predictability with fair accuracy could be possible in the near future, as compared to a current 10-day period. The increasing ability of supercomputers allow higher resolution models to be made when capturing information from satellites and weather balloons. Conditions that are captured include temperature, pressure, humidity, and wind speed.

A Canadian Radar Weather Station near Vernon BC. Wikimedia Commons

The 2-week period is believed to be the upper limit, as weather patterns follow “The Butterfly Effect“, discovered by Edward Lorenz. Minuscule disruptions, such as a butterfly flapping its wings can eventually snowball into a much bigger tornado far away. Even very tiny differences in starting conditions, over the course of two weeks, can turn into widely varying weather conditions based on the same predicting model. Uncertainty in the conditions observations and in the model can end up leading to a large variation in predicted weather. This makes anything beyond the 2-week period unlikely to be predicted accurately as the uncertainty grows over time.

The following video by Lloyd Treinish shows how weather forecasting systems work and how they can be used to prepare for the weather before they even happen.

Since these weather forecasting models help governments and business to determine how to keep the public safe and minimize financial losses, the science behind it is crucial and early forecasting allows more time to prepare for upcoming weather emergencies. So, if  you’re desperately hoping they cancel that midterm, you can trust that the weather forecast will not let you down.

Christy Lau

The New and Improved Kilogram

How do we know how much anything weighs? Where does the measurement come from when you use the kitchen scale or the scale in your physics lab? Since 1879, the sole definition of the kilogram was carefully locked away in an underground vault in France, the International Prototype Kilogram (IPK). Starting May of 2019, this tightly stored piece  of platinum and iridium will no longer officially represent the mass of a kilogram. This renewed definition will be more accessible to everyone and remain accurate for the rest of time, demonstrating the importance of this change.The kilogram is one of the base units as part of the International System of Units (SI).

The International Prototype Kilogram, or Le Grand K informally, is the only physical artifact that determines the official mass of one kilogram. However, since it is stowed away under careful protection by the International Committee for Weights and Measures (ICWM). It is hardly accessible and any changes in mass due to scratches or dirt would change the official mass of the kilogram. Even copies made of Le Grand K may not always be exactly accurate.

This prompted the change by the ICWM to a much more accessible and unchanging value based on a fundamental constant, the Planck’s constant. Planck’s constant, or h, like all other fundamental constants of nature remain the same with time and throughout the universe. Planck’s constant relates the smallest energy packet possible to the frequency of that energy packet, and is defined to be 6.626176 x 10^(-34) kilogram meter squared per second. With the kilogram within this constant, the determination of the kilogram can be made much more precisely without needing to compare it with the actual IPK.

To determine the mass with the new definition, a Kibble balance can be used. The Kibble balance is able to weigh mass against an electromagnetic current, making it incredibly accurate and precise.

Shown below is a video from Veritasium working with NIST (National Institute of Standards and Technology) explaining the new changes for the kilogram and how a kibble balance is used to determine the mass:

For the common household scale, or even anything beyond advanced physics, the new definition of the kilogram will not cause any change in mass. However over time, the required precision for mass in all fields of science will benefit from this change. The importance for consistent and precise measurements in all of science and business are seen.

— Christy Lau