Site Owner & Radio Enthusiast
According to MediaTracks Communications, most radio listeners tune in between 7 a.m. and 6 p.m.
Although it’s unclear from the data if listenership includes AM, there might be a case for listening later in the day. Is AM better at night?
AM radio is better at night due to the landscape of the ionosphere, which changes after sunset. The signals can travel much further due to what’s known as sky-wave propagation.
Additionally, some AM stations must stop operating after dark to reduce interference, which also helps some stations come through more clearly.
Read on if you’re interested in understanding why you can more clearly hear AM radio at night versus the daytime!
Why Is AM Radio Stronger at Night?
If you’ve tuned into AM radio after dark and noticed the station comes in much stronger and more clearly than listening by day, it’s not simply your imagination.
This is a phenomenon that’s explainable through science.
AM radio’s propensity for a better signal at night is due to the ionosphere, a layer of the planet’s atmosphere between 50 and 600 miles over the earth’s surface.
As a name like the ionosphere might conjure, this layer contains many ions.
It’s not only ions present but free electrons.
How the ions and electrons behave depends on which part of the ionosphere we’re talking about.
The upper layers, the F1 and F2 layers, have a lower atom and molecule density, encouraging free electrons to remain solo before they combine with other electrons.
In the lower layer, called the D layer, the molecules have more density and recombine rapidly.
These electrons and ions are created during the day when the sun increases the ionization rate.
They’re temporarily unpaired. The electrons in the D layer seek to combine with whatever they can, and not necessarily other electrons. Radio waves work just as well.
Radio waves are quickly absorbed when they enter the ionosphere during the day. This severely impedes their ability to travel.
So what happens to the ionosphere without the sun? It changes. Ions and electrons continue to recombine.
You can imagine the ionosphere as a crowded party and yourself as a radio wave trying to navigate the crowd.
When everyone is standing around alone, it’s a much bigger throng to contend with.
However, when people pair up, the crowd seems more navigable.
That’s how radio waves can travel further through the ionosphere after the sun goes down.
The radio waves benefit even in the F1 and F2 layers, where recombination happens more slowly. Here, they can bend or refract toward where they came from.
This entire phenomenon is known as sky-wave propagation.
The FCC’s Involvement with Stronger AM Radio Signals at Night
However, it’s not merely sky-wave propagation that improves AM signal strength after dark. The FCC also plays a role.
According to FCC rules, many AM radio stations must stop operating or reduce power when airing at night. This is designed to minimize interference.
This rule is part of the FCC’s broader frequency plan, which includes allowable frequency allocations.
You might recall from our article about whether people listen to AM radio that about 6,000 stations are spread across the airwaves as of the early 2020s.
Some can use clear channels at night but frequently employ a directional antenna.
The antenna will reduce interference when operating on the clear channel station, providing a better listening experience for all.
If an AM station cannot obtain a directional antenna or other protections to lessen the rate of interference, the FCC will only permit them to operate the station by day.
Before you tune into your favorite AM station, use the FCC’s handy tool, AM Query Broadcast Station Search.
You can search for any AM station broadcasting between 530 and 1700 kHz. You only need to know its call sign to begin searching; even a partial call sign is fine.
How Much Further Can AM Radio Signals Reach at Night?
Why the need to curtail AM radio signals by night at all? Can they really travel that much further once the sun sets?
Indeed, they can!
AM radio at night can extend hundreds of miles beyond the same signals during the day.
This can extend your radio listening experience to other parts of your state or adjoining states.
Depending on where you live, you might even be able to enjoy AM radio outside of your home country without crossing a border.
The Role of Sunspots in Improving AM Radio by Night
If you’re a ham radio enthusiast, you might have heard people in your circle get excited when sunspots are in the weather forecast.
Sunspots occur in the photosphere, a different layer from the ionosphere. They look darker than the rest of the sun due to their lowered surface temperature and higher magnetic field.
The umbra, which is the middle area, reaches temperatures of only 6,300 degrees Fahrenheit, whereas the rest of the photosphere is up to 10,000 degrees, says the National Weather Service.
They occur when magnetic flux builds up and reflect the rate of solar activity the sun experiences.
So what do sunspots have to do with AM radio?
The sun ionizes more when sunspots occur and during other high solar periods.
The better the ionization, the stronger the signal for AM radio by nightfall.
Why Is My AM Radio Signal Still Fuzzy at Night?
While AM radio signals can travel further at night, that doesn’t mean you’re always guaranteed to get a strong signal.
Let’s assess why you might hear crackles, pop, and static.
AM stations are not impervious to interference even when the moon rises.
Power lines can cause interference, as can the equipment across your home, from garage door openers to LED and fluorescent lights, washers and dryers, computers, power supplies, light switches, electric drills, and even your phone charger.
Remove yourself or your radio from the source of interference if you can and see if that improves the AM signal.
Another thing you can do is adjust the antenna of your radio.
If you travel a lot with your radio, the antenna can loosen over time, so tighten it first.
Secondarily, straighten the antenna and see if that makes a difference.
Check the antenna base. Do you see corrosion? If so, use an anti-corrosion product or try cleaning it.
If you can’t remove it, you’ll have to replace the radio’s antenna, as corrosion contributes to how well the antenna works and, thus, how strong of a signal you get.
The last possible contributor to a fuzzy AM station is that the station is forced to lower its power per FCC regulations.
If the station doesn’t operate at full power, the audio quality may not be as strong as when listening at other times.
We recommend checking the above FCC list to see if your preferred station has to reduce power at night.
If yes, that solves your problem.
If not, and the lack of audio clarity persists, try the other methods discussed in this section.
AM radio is markedly better at night due to ionosphere changes.
The rate at which molecules bond across the ionosphere increases at night, allowing radio signals to travel further, sometimes hundreds of miles further!
However, the FCC has regulations on which AM stations can broadcast and when, requiring some to have a license or other permissions to stay on the air at night if they don’t have signal-protecting devices.
The next time you go to listen to AM radio on your short-wave ham radio, do so at night. You should certainly enjoy the experience!