Imagine if you could predict weather just by looking at clouds and finding simple clues of upcoming weather.
This is certainly one of the most impressive skills for anyone who develops nature observation skills.
So how is it done? And how accurate is it really?
In today's article, let's explore this incredibly exciting and practical naturalist technique... And discover that YES predicting weather by observing nature is totally possible.
Just by looking for basic patterns in cloud type, wind direction, and combining those observations with accumulated knowledge of how weather works, you can learn to tell when pressure is changing and storms approaching.
What are the signs of approaching rain?
How to predict how large the storm will be?
How many hours will it be before the storm arrives?
Let's start off by talking about one of the best indicators of current and upcoming weather patterns. The clouds.
A Guide For Reading Clouds
Clouds are not just puffy white balls of moisture in the sky.
To the astute weather watcher they are actually like the pages of a book, and they have fascinating stories to tell you.
Just as a skilled tracker of the African lion knows how to read the meaning of tracks & sign on the african savannah...
So you can learn to read the clouds and form accurate conclusions about upcoming rain and pressure systems.
2 Basic Types Of Clouds
It's important to keep things simple.
While it is possible to geek out on dozens of different types of clouds, the vast majority of clouds are actually simple variations on two basic types.
My suggestion is to learn these basic cloud types first. Then it will be much easier to narrow and get more specific.
You're probably already familiar with cumulus clouds whether you realize it or not. If you've ever spent a summer afternoon spotting sheep, elephants & unicorns in the sky, you were probably looking at cumulus clouds.
In layman's terms, you might call these "clumping clouds" (because they clump together).
Here's a photo example of a basic cumulus cloud. Notice there are several "clumps" of puffy white clouds.
Cumulus clouds tell you that condensation is starting to gather at a particular altitude in the sky (more on this in the section on cloud altitudes).
You can also tell how much condensation is in these clouds by looking at the height and depth of a cloud. In the example above our cumulus clouds are relatively small and flat like a pancake.
But cumulus clouds can also grow very tall and deep like a triple stacked ice cream cone.
Here's an example of active growth in a cumulus cloud...
Notice the upward expanding puffiness at the top of the cloud.
This is a sign that condensation levels are growing more aggressively, causing the cloud to expand outwards and upwards.
And once this cloud reaches a certain threshold of condensation... guess what happens? You get rain!
Another very common type of cloud is a stratus cloud, but an easier way to describe them is "layered" clouds.
Stratus clouds don't form as balls or clumps. Instead, they spread across the sky like butter on a piece of bread.
One of the most common examples of stratus clouds is fog as shown in this photo.
As with cumulus clouds discussed above, stratus clouds tell you that layers of condensation are forming at a particular altitude in the sky.
These layers of condensation spread out over long distances that frequently cover the entire area of the sky.
Yet, often you'll be able to see right through these layers.
If you ever notice halos around the sun or moon it's because you're looking through the haze of a stratus cloud.
However, as stratus clouds become very thick and dense, again the result is rain.
Quick Fact: Stratus clouds produce a different type of rain from cumulus clouds (More on this in the section about clouds that produce rain).
The Importance Of Cloud Altitude
The real magic of cloud identification comes when you realize that different cloud types form at various levels of altitude.
These different cloud levels play a HUGE role in helping you determine what kind of weather might be moving through over the next few days so you can start to predict the timeline of approaching rain or storms.
I was shocked to discover just how easy it is to spot the differences between low, medium and high altitude clouds.
Both cumulus and stratus clouds exist at levels anywhere between 1000 feet and 60,000 feet... but there are subtle differences in the form they take at each different level.
Here are the three levels of clouds (and what they tell you). Low Level Clouds
The examples of basic cumulus and stratus clouds I gave earlier both came from the lowest level of cloud cover.
These are the puffy white clumps and fog respectively. They're both very common in fair weather conditions.
But both types of clouds can also occur at higher altitudes... where they take on a slightly different form.
Medium Level Clouds (Alto)
Medium level clouds occur anywhere in the range of 7000 to 25000 feet high. These clouds often tell you there is rain or snow is approaching, even though the weather might still feel gorgeous.
Medium level clouds can also happen after a storm as a weather system moves away, or when there is bad weather passing by but not directly affecting your location.
Again there are both Cumulus & Stratus type clouds at this level.
Here's an example of AltoCumulus:
Notice how the clouds are again forming in clumps, making the sky look a bit mottled.
AltoCumulus are an indicator that an earlier cloud is being broken up by wind. This could have been a layer of stratus or cumulus just a few hours ago.
Similarly, Altostratus clouds also form in the medium level of altitude.
Notice the layers spreading out from the horizon. You can also tell the wind direction by looking at the direction these clouds point.
The important thing to remember here is that the particular layer where Altostratus clouds are forming indicates a shift in pressure.
You'll often see clouds like this before the approach of a storm (More on this in the section on spotting approaching weather).
High Level Clouds (Cirrus)
Cirrus clouds form at very high altitudes. So high that condensation happens in the form of ice crystals.
Cumulus and Stratus type clouds once again take on a new form at this highest level of clouds.
Cirrocumulus clouds are high clouds that form in tiny clumps. Cirrostratus clouds are high clouds that stretch out like a uniform layer of white.
You'll see examples of both in this picture:
These subtle clouds are often the earliest indicator that weather is going to change soon... although it can still take days for more obvious rain clouds to appear.
If you ever notice the highest levels of the sky becoming filled with cirrus clouds that spread out more and more... You might be witnessing the approach of a weather system.
Look for signs of increasing instability on the middle and lower cloud levels over the next 24-48 hours to determine whether there's a storm coming!
Clouds That Produce Rain
There are 2 types of clouds that produce most rain.
And did you guess it? One is in the cumulus family, while one is in the stratus family! These are Nimbus clouds.
Let's discuss the different types of rain they bring.
Another way of saying cumulonimbus is that it's a cumulus cloud that has gotten so big that it rains cats and dogs.
This type of rain is often produced by warm, humid air rising on thermals in summertime. It's what's sometimes called, "summer rain".
CumuloNimbus clouds can drop a large amount of precipitation in a very short period of time. It could be sunny at 1pm, pouring rain at 1:30 and Sunny again at 2pm.
Here is a small cumulonimbus cloud:
Notice how the cloud extends upwards with great vertical depth. These clouds will frequently extend all the way through the lower & middle levels of the sky.
But they often occur alongside sunshine and beautiful hot weather. Notice the rain coming out the bottom. NimboStratus Clouds
Likewise, Nimbostratus clouds are simply stratus clouds that have become so big and dense that they drop rain.
Notice how in this example you really can't even tell where the cloud begins and ends. It's very dark and covers a large area of the sky.
One of the big differences between nimbostratus and cumulonimbus clouds is that nimbostratus lasts a long longer. They stretch out to cover the entire sky as far as you can see.
If there's no wind to push the clouds away then it can sometimes stay over head and rain in a looming way for days at a time.
These clouds also produce large amounts of snow in cold weather.
How To Spot Approaching Weather Systems
Just because you know how to identify clouds, doesn't mean you can accurately predict weather.
A single cloud usually doesn't say all that much... but combined with a SEQUENCE of changes in the architecture of the sky you can get a real sense for shifting patterns.
Here are two examples of cloud sequences indicating that bad weather is approaching. These signs can be seen anywhere from a few hours to an entire week before the storm arrives.
Scenario #1 Nimbostratus approaching
High cirrus clouds form at the leading edge of where warm air meets cool air. You'll notice the highest levels of the sky become more and more busy with whispy ice crystals and airplane contrails. Look for cirrus clouds. Also note the direction they're coming from.
Medium level clouds start to move in and become more dominant. The cloud coverage will slowly increase until the entire sky is filled, though you might still be able to see the sun. Look for Altostratus and or Altocumulus. The system is getting closer but you still have time.
A giant layer of stratus type clouds fills the entire sky. These clouds become darker and more dense until they completely obscure the sun. The darkness continues to grow until rain starts.
This entire process sometimes takes days to occur. The faster this progression occurs indicates how soon the rain will start and finish.
Systems that take a long time to develop will probably be much larger, last longer and bring more precipitation.
Other times a small, fast moving system can develop and move through in less than a day.
Scenario #2 - Cumulonimbus Developing
Morning starts and you notice small puffs of low level cumulus clouds floating across the sky.
As the day heats up the small puffs start to expand upwards. You can see signs of active growth cause by late morning thermals.
Eventually these clouds become so congested and vertically deep that they begin to expand outwards and upwards at a massive rate.
When the cloud gets large enough it will drop large amounts of localized rain, possibly followed by sunshine, rainbows, and the intense smell of summer rain.
There are of course other ways that systems develop such as when warm humid air is forced up over a mountain... but the same basic observation principles apply in all situations.
Using All Your Senses
It's important to remember that using awareness to predict weather is about more than using your eyes.
Your 5 senses all have helpful things to tell you. You'll get better at honing your intuition about weather by tuning in with as many different signs as possible to confirm your weather hypotheses.
Here are some examples:
Rising humidity will cause your sense of smell to work better with approaching rain.
Humidity is also easier to sense through the air in your nose than through your skin. Don't just sniff for scents... pay attention to how the air feels in your nostrils.
Birds will change their behaviour and become more active before and after storms. You might notice sudden influxes of rare and vagrant birds being pushed out ahead of a storm system.
Some flowers like dandelions will respond to drops in pressure by closing their petals. Next time you're out harvesting dandelions for food remember to look for how open the flowers are.
Each ecosystem has it's own unique patterns. What is normal for your bioregion? Does weather usually develop quickly or slowly in your area?
Folklore And Weather Wisdom
There's also lots to be said about folklore and old wisdom concerning weather.
Human beings have been watching weather for thousands of years leading to endless sayings and rhymes that can provide insight.
Some of them are totally bogus, but others are backed by good science.
This example from the book, Weather Wisdom by Albert Lee:
Is a reference to the fact that in many parts of the world, the east wind is a really good sign of approaching storms.
And likewise the old saying,
Is a reference to the weather conditions that turn a sky red at sunrise and sunset.
Red skies occur when the low sunlight at sunrise or sunset reflects against medium level clouds that commonly before or after poor weather.
If you live in a part of the world where the weather tends to move from west to east... then a red sky at night means the sky is clear in the west.
If however, the red sky occurs in the morning it means the rain is probably heading your direction. (More information about this on wikipedia)
It's important to remember these old sayings are still generalizations of how weather works in the specific region & culture where they developed.
They're a great place to start growing your awareness but you should always test and observe to confirm their accuracy in your climate.
There's a lot more that could be said about weather prediction.
For now here are some practical steps you can take to improve your nature observation skills by looking at clouds and weather.
Learn to identify the difference between cumulus and stratus clouds at low, medium and high levels of altitude.
Learn to identify the signs of active growth in cumulus clouds
Keep a journal of sky sequences. Try to spot the approach of weather systems by seeing how the cloud layers fit together. What happens in the 24 hours after you see cirrus clouds? What happens 24 hours after that?
Practice using your senses outside. Spend time sitting in nature and focus on the clouds & weather. Note the wind directions too.
Let me know what gets you excited about weather. What questions do you still have?