Written by Seth Carrier, NIWA Meteorologist/Forecaster
On this page:
- Did you know that you can get a job studying and predicting the weather?
- Experiment – make a cloud in a bottle!
- Quiz – intro to weather and meteorology
Download a shorter version of this lesson in PowerPoint or as a PDFor continue below to see the lesson in full.
You probably hear the word weather almost every day, but what is it really? You can think of the weather as what you see out your window every day. Is today sunny, cloudy, windy, rainy or stormy? All of those things are part of the weather.
Weather is what we see and feel in the short-term, meaning over the next few days or the next couple of weeks. When we look at trends in the atmosphere over longer time frames, such as months or years, that is called climate. We will look at climate more closely in a later lesson.
One of the most noticeable aspects of weather are clouds. You see clouds almost every day, but maybe you’re wondering how they form and why they’re able to “float” in the sky.
It might be hard to believe, but clouds are made up of billions of tiny water droplets. All air holds water, but near the ground it’s usually in the form of an invisible gas called water vapour. If this air near the ground is warmer than the surrounding air, it begins to rise. The rising air cools as it gets higher in the sky, and cool air can’t hold as much water vapour as warm air. At this point the water vapour condenses (changes from a gas to a liquid) around very small pieces of dust floating in the air and a tiny water droplet is formed. When billions of these droplets come together you have a cloud!
Why do clouds float in the sky?
Because clouds start as warm air, they have a higher temperature than the air around them. As long as a cloud is warmer than the air around it, it will float in the sky.
Why are clouds white?
Sunlight is made up of all the colours of the rainbow and together these appear white. When sunlight hits a cloud, the water droplets inside the cloud are big enough to scatter the light of all seven colours almost equally, making the cloud look white too.
But why do rain clouds usually look grey?
In rain clouds, the water droplets are larger and scatter light more, meaning less light makes it out of the bottom of the cloud and it looks darker.
How do clouds move?
Clouds are pushed along by the wind at their level of the atmosphere. Usually low clouds move slower than high clouds. In fact, high-level cirrus clouds (see below) can move over 160 kilometres per hour! That’s much faster than a car travelling on a motorway!
Common types of clouds
Cirrus clouds: These are the highest clouds, usually forming above 6,000 metres. In fact, these clouds are so high and so cold that they’re made of ice crystals instead of water droplets! They look thin and wispy as strong winds high in the sky blow them into long streams. Cirrus clouds can indicate that the weather is going to change for the worse over the next 24-36 hours.
Cumulus clouds: These clouds are fluffy and white and look like cotton balls floating in the sky. Cumulus clouds often form only around 1,000 metres above the ground.
Cumulonimbus clouds: Tall, ominous-looking clouds that can become thunderstorms. Expect heavy rain, lightning, hail, and maybe even tornadoes when you see these clouds.
Stratus clouds: Flat, grey clouds that cover the whole sky. These clouds usually produce drizzle or light rain.
Fog: Fog is just a regular cloud that forms at ground level. Fog typically forms when warm air blows over much colder soil or even snow.
A variety of types of clouds shown by typical atmospheric altitude. [Valentin de Bruyn / Coton]
Valentin de Bruyn / Coton [Wikipedia]
One of the main things we have to watch to understand the weather is the presence of low and high pressure.
Areas with low pressure are usually associated with bad weather. If an area has low air pressure, air from neighbouring areas with higher air pressure, will move in and force the air to move upward, as it has nowhere else to go. When the air moves up, the water vapour will condense and lead to the formation of clouds and rain.
Areas with high pressure, are typically associated with good (happy!) weather. In high-pressure areas, the air sinks toward the ground, leading to dry, pleasant weather and usually lots of sunshine!
Along with high and low pressure we also find fronts. A front is a boundary between two different air masses (usually one warm and one cold), and along fronts there is often stormy weather, sharp temperature changes, and rapid shifts in wind direction.
A cold front divides warm air and cool air, moving so that the cooler air replaces the warmer air. A warm front works in the opposite way, with warmer air replacing the cooler air.
It’s true! People who study the weather are known as meteorologists, and you’ve probably seen them talking about the weather on television before. Other meteorologists work at airlines, power companies, or might even tell the Black Caps if their match may be delayed by rain.
Most meteorologists go to university for at least four years to learn how to predict the weather, and some even longer! Even after graduating from university, it takes lots of practice to get good at predicting the weather, and meteorologists are always learning.
What is a meteorologist?
You see clouds in the sky almost every day. Now it’s time to make your own!
What you'll need:
- A clear 2-litre plastic bottle
- Warm water
- Matches (ask an adult for help using the matches)
- Fill the bottle two-thirds full of warm water and screw the cap on. As warm water evaporates, it adds water vapor to the air inside the bottle. This is the first ingredient to make a cloud.
- Squeeze and release the bottle and observe what happens. You’ll notice that nothing happens. Why? The squeeze represents the warming that occurs in the atmosphere. The release represents the cooling that occurs in the atmosphere. If the inside of the bottle becomes covered with condensation or water droplets, just shake the bottle to get rid of them.
- Take the cap off the bottle. Carefully light a match and hold the match near the opening of the bottle.
- Then drop the match in the bottle and quickly put on the cap, trapping the smoke inside. Dust, smoke or other particles in the air is the second ingredient to make a cloud.
- Once again, slowly squeeze the bottle hard and release. What happens? A cloud appears when you release and disappears when you squeeze. The third ingredient in clouds is a drop in air pressure.
Water vapour, water in its invisible gaseous state, can be made to condense into the form of small cloud droplets. Adding particles such as the smoke enhances the process of water condensation and by squeezing, and then releasing the bottle it causes the air pressure to drop. This creates a cloud!
Check out our weather and meteorology quiz over on Kahoot.
(The quiz works best on kahoot, but if you prefer a text version, you can download it as a PDF here).
- Thermometer for measuring air and sea surface temperature.
- Barometer for measuring atmospheric pressure.
- Hygrometer for measuring humidity.
- Anemometer for measuring wind speed.
- Pyranometer for measuring solar radiation.
- Rain gauge for measuring liquid precipitation over a set period of time.
There are many different instruments that can be used to measure the weather. Some examples are the thermometer, hygrometer, anemometer, barometer, rain gauge, and the wind vane.
- Weather Forecasting and Warnings. ...
- Atmospheric Research. ...
- Meteorological Technology Development and Support. ...
- Information Services. ...
- Forensic Services. ...
- Broadcast Meteorology. ...
Aristotle is considered the founder of meteorology. One of the most impressive achievements described in the Meteorology is the description of what is now known as the hydrologic cycle.
There are six main components, or parts, of weather. They are temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness. Together, these components describe the weather at any given time.
Weather is made up of six main components. These are temperature, atmospheric pressure, cloud formation, wind, humidity and rain. A small change to any of these conditions can create a different weather pattern.
The eight elements that are observed by the meteorologists for making weather forecasts are air temperature, wind direction, humidity, wind speed, clouds, precipitation, visibility, and atmospheric pressure.
They protect the temperature sensors from being influenced by direct or reflected sunlight. Stevenson screens are always painted white to better reflect the sun's rays. The louvered sides allow outside air to flow around the thermometers.
It forms part of a standard weather station and holds instruments that may include thermometers (ordinary, maximum/minimum), a hygrometer, a psychrometer, a dewcell, a barometer, and a thermograph.
- Wind velocity and direction.
- Cloud formation.
This video by Mike Sammartano explains how six common weather instruments work: thermometers, barometers, sling psychrometers, anemometers, wind or weather vanes and rain gauges.
You may already be familiar with common weather instruments, like thermometers and wind vanes. But to get the full picture of the weather around us, we need hygrometers, anemometers, barometers, rain gauges and sometimes even lightning detectors.
The barometer is one of the most important instruments in weather forecasting. It is used, as the name suggests, to measure localized atmospheric air pressure. Evangelista Torricelli is widely credited with the invention of the barometer in the mid 17th Century.