The Wonders of the Weather App
Do you ever find yourself scrolling through the weather app on your phone and wondering what all the displays mean? Well, you’re reading the wrong blog if you haven’t. Or maybe, this will be your weather app awakening. Who knows.
My job today is to run you through the weather app the best I can. First, I will label some screenshots of my weather app with letters. Below that, I will add descriptions of each section. If I feel that any section needs further explanation I will dive deeper into what exactly it means (at least to the best of my knowledge). After this, you will know everything you need to know when you open your weather app! 🤩 (*Note, if you click on any of these widgets on your own weather app, you will be able to see the information displayed more in depth which I actually figured out while writing this blog post.)
A: Main Page – I truly hope you understand everything seen here, and if you don’t…meteorology might not be your thing. But, if you’re willing to put in the hard work, you can do anything 😌👍
B: Air Quality – Air Quality Index (AQI) provides daily air pollution concentrations. The intervals on the scale relate to potential health effects1 (see table below).
C: Radar – Shown on the screen is the radar for precipitation. But, how does a radar work? You might ask. Well, I had the same question so pulled out my handy-dandy textbook (thanks Ms. Allen 😊) and went to investigate. Similar to how a doctor might use an X-ray, meteorologists use radar to see what is going on inside a cloud (most likely a cumulonimbus). They send microwaves at the cloud and then an echo is received by the radar. The “brightness” of the echo determines the intensity (amount) of the precipitation and the type. This allows meteorologists to accurately predict where the precipitation will fall and how intensely. Nowadays, we use a doppler radar which measures not only the brightness of an echo but also the frequency (doppler shift = when a siren passes you the pitch (frequency) gets lower the further it is from you). This gives meteorologists more information on which direction the precipitation is going.3
This widget can also show temperature, air quality, and wind, which are, hopefully, more self explanatory so Imma let you figure those out 😁
D: UV Index – (see table below). Sooooo…why do UV (ultraviolet) rays cause sunburns? Well, other than X rays, UV rays have the most energy carried per photon. This means they have enough energy to burn your skin.
E: Sunset/Sunrise – This widget shows what time the sun rises and sets. This one is just cool to see.
F: Wind – This section shows wind speed and gust speed. Gusts are “ a sudden increase of the wind’s speed that lasts no more than 20 seconds.”5 So, what this info in the picture means is that the wind is blowing at about 4 mph and in 20 second bursts, the wind gusts are reaching 9 mph.
G: Feels Like – This section takes into account wind chill (usually during the winter) or heat index (usually during the summer). Both of these measure the temperature in addition to humidity and wind to more accurately describe how the temperature feels and its effects. During warmer days, higher humidity increases the “feels like” temperature because it stops your sweat from evaporating, thus stopping you from cooling down. On the other hand, wind chill happens on cooler days because when wind blows away the warm air our body makes, we get cooler.6
H: Precipitation – I trust that you know what this is displaying so I’m just going to leave it at that.
I: Visibility – According to my beloved weather app, “visibility tells you how far away you can clearly see objects like buildings and hills. It is a measure of transparency of the air…Visibility at or above 6 mi is considered clear.”7
J: Humidity – Humidity is a broad word so I’m gonna break it down a bit. The humidity the app is referring to relative humidity. Explained more deeply in the previous blog post, relative humidity is the percentage of how much water vapor is in the air out of how much water vapor the air can hold in the present conditions. In the smaller text below the percentage value is the dew point. This is something I have yet to talk about so I’m gonna offer a brief summary and then go deeper so if you want to nerd out with me, you are certainly welcome to. Simply stated, dew point is the temperature at which water vapor condenses in certain conditions. In other words, dew point is the temperature at which evaporative cooling stops. Evaporative cooling is what happens when we sweat: our body produces moisture and the moisture evaporates which cools us down. Evaporative cooling stops when the temperature gets cool enough that the water can’t evaporate anymore which is the dew point. According to my meteorology textbook, “The dew point is a good indicator of the air’s actual water vapor content. High dew points indicate high water vapor content; low dew point, low water vapor content.”8 I find this wording hard to understand so let me rephrase: water condenses at a higher/warmer temperature (high dew point) when there is a lot of water vapor in the air because it doesn’t need to get as cool for water vapor to start sticking together. On the other hand, when the air is drier/has less water vapor, the temperature for water to condense at is lower/cooler temperatures because there is less water vapor readily sticking together. Does this make sense? I kinda just have to sound it out to understand it so I brought you along through this process. AND this all connects back to relative humidity: when relative humidity is high, dew point is also high and vice versa.
K: Moon Phases – Another widget that just shows something some people might like to know on the daily but doesn’t affect everyday weather all that much (I think).
L: Averages – This historical average display is SO COOL omg. I think it is fantastic to have a visual seen daily by most people that gives people a chance to see this year’s weather in comparison to the “the most common temperatures [for each day] since 1970.”9 To me, because I focus more on the climate change aspect of meteorology, I like this widget specifically because it shows you how much the weather has changed since the 1970s. Although this screenshot shows that the temperature is below average. The past couple of days (Jan 25 or Jan 26, for example) have seen a wide gap of about 25ºF above the average!
M: Pressure – Last but not least, is barometric pressure. As mentioned in the previous post, barometric pressure (AKA atmospheric pressure, AKA air pressure) is “the force exerted by the air molecules over a given area.” This means the pressure is higher the closer to Earth’s surface you are, and there are also high and low pressure systems that roll through the world. “A barometric reading over 30.20 inHg is generally considered high, and high pressure is associated with clear skies and calm weather. A barometric reading below 29.80 inHg is generally considered low, and low pressure is associated with warm air and rainstorms.”10 Finally, inHg, which means inches of mercury, is a unit that comes from the first barometer made which was a thin glass tube set in a container of mercury. When the pressure is high, the air pushes the mercury in the container down which then sends the excess mercury into the glass tube. When the air pressure is low, the air doesn’t push down on the mercury in the container so the glass tube is less full.
1: Meteorology Textbook (Essentials of Meteorology – An Invitation to the Atmosphere, Eighth Edition, by C. Donald Ahrens and Robert Henson)
3: Meteorology Textbook
7: Weather App on my iPhone
8: Meteorology Textbook
9: Weather App
Wow! I learned way more than I expected to. I will never look at my weather app the same way, but rather will now appreciate all that it is telling me. Thanks Weather Nerd!
Excellent description of barometric pressure. Good work there. My comment on Doppler is in an email. I very much likely concept of explaining the data. Good work. Thanks for sharing