The difference between weather and climate and how they are related
The Five components that generate climate
The Köppen climate classification system
Climate change
After the TV weather person makes their report and prediction on the local station, many times there will be a short clip about the climate, often with dire warnings of how changes are going to mess everything up and that it is all mankind’s fault. You may have heard people say things like
“The weather is going to be exceptionally hot today, it must be because of global warming” or “We had a really bad winter last year because of climate change”.
These statements can be confusing because weather and climate are related, but they are not the same thing. On the NASA Climate page, it says that
“The difference between Weather and Climate is a measure of time”
and even that is not quite accurate. Comparing weather and climate is not like comparing apples and oranges, nor is it like comparing an orange to a crate full of oranges. It is more like comparing oranges to fruit. In other words, oranges are fruit, and there are many fruits that have a lot in common with oranges, but not all fruit is like an orange.
Weather is an important part of climate, and when we classify climates one of the important things to look at is the average weather over an extended period of time. The climate of a certain region is generated by the interaction of five worldwide components:
the atmosphere where weather is generated
the hydrosphere which is the mass of water found on below and above the planet
the cryosphere or regions of solid ice such as the polar caps
the lithosphere or rocky outer shell of the planet
and the biosphere or the living things on the planet.
The most common way of classifying climates is using the Köppen Climate Classifications. The classifications were first published in 1884 and have been modified several times since. They were originally based on the notion that native vegetation is the best expression of climate.
The system is divided into five main groups (A, B, C, D, E) and each group is further divided into types. Each climate type may be represented by a 2-4 letter symbol. For example, Miami has an A or Tropical monsoon climate; Denver has a B or Dry Steppe climate with at least one month of average temperatures below freezing, Los Angeles has a C or Mediterranean climate with hot and dry summers dominated by subtropical high-pressure systems, and Chicago has a D or Continental climate with the warmest month averaging greater than 72°F. Group E climates are polar and alpine zones.
The Köppen climate classifications are useful for travelers and geography students as well as those studying weather and climate.
Paleoclimatology is the study of ancient climates and weather patterns before modern record keeping. We know that the worldwide climate has changed many times, just like it is changing now. There are many theories and reasons behind climate change ranging from an “end of the world” scenario caused by pollution and other manmade factors to a natural cycle that would occur no matter what man does.
This is not a forum to debate the various causes of climate change, let alone fix blame. We will just point out that climate change is happening, it has happened before, and species and civilizations who can adapt will survive and thrive.
Review Quiz:
Q1:What are the five world-wide elements of climate?
Q2: What expression of climate are the original Köppen climate classifications based on?
Q3: What can the study of paleoclimatology teach us about climate change today?
Answers:
A1: The atmosphere, the hydrosphere, the cryosphere, the lithosphere and the biosphere.
A2: The system was originally developed by Wladimir Köppen, who was a botanist as well as a climatologist. He based his climate classification system on the observation that certain types of plants grow in certain regions but not in others. In the decades since the Köppen climate classifications has come into use, we have a better understanding of how a saguaro cactus and a live oak tree have different climatic needs, and how climate change over time affects how plants grow and thrive
A3: Through paleoclimatology, the study of climate before records were kept, we know that regional and planet wide climates change. These cycles are not entirely predictable, and it is inconclusive how much effect man-made factors have influenced climate change.
How weather is what is happening in the atmosphere
The difference between climate and weather
How heat from the Sun is the energy that drives weather
Introducing how moisture in the air absorbs and releases energy
Every day before you go outside you probably take a look out the window to see what the weather is doing. Most people are happy if it will be sunny and warm so they can put on shorts and play in the backyard, and if it is rainy and cold they would rather stay indoors with a warm drink.
It is easy to think of weather as simply being nasty or nice, but there is a lot more going on than just these two opposites. Weather is what is happening in the atmosphere at a particular place, and the weather is always changing.
There is weather inside your house as well and we will be looking more closely at the inside weather to help us understand how the weather outside works.The climate is in the news a lot these days. Climate and weather are related, but they are not the same thing, and it is hard to understand climate until you understand weather.
Weather is what is happening in the atmosphere at a certain time at a certain spot while climate is a study of the weather in an area over a long period of time.
Looking out the window seems pretty simple, we see that it is either sunny or cloudy, windy or calm. In fact, many different things influence what the weather is doing in your backyard. Some of them are hundreds or thousands of miles away from where you are. The two most important things that affect the weather are heat and moisture.
The heat comes from the Sun shining on the Earth. Since the Earth is tilted relative to the Sun, the area around the Equator receives more heat than at the poles. Also, the Earth is spinning, so the everywhere that the Sun is shining now will be in darkness in a few hours.
In general, warmer air rises and cooler air comes in to replace it. The new air warms and the cycle continues. It’s like putting a big pot of water on the stove to boil; the water in the bottom of the pot near the middle gets hot first because it is closest to the fire. We can see the water in the pot begin to circulate in a process called convection.
As the hottest water in the bottom of the pot moves up, it cools a little bit and the cooler water moves to the bottom and begins to absorb the heat from the element. When all of the water in the pot becomes so hot that it cannot absorb any more heat, it boils.
The heat from the Sun is the energy that drives the weather, just like gasoline is the energy that drives a car. Just a tank full of gas will not make a car move, of course. It needs an engine to convert the energy of the gasoline into motion. The engine in the atmosphere that drives the weather is water, or more specifically moisture.
You may have been taught that water exists in three states of matter: solid, liquid, and gas in the forms of ice, water and vapor or steam.
We are told that water changes between these states according to temperature: water below 32°F occurs as frozen ice, between 32°F and 212°F water is liquid and above it is steam. However, there is another factor that is just as important as temperature to determine the physical state of water; pressure.
Let’s go back to our pot on the stove. What if we went outside and filled the pot with snow?
As soon as we brought the pot inside the ice in the snow begins to melt, and it melts even faster when we put it on the stove. Not only does it get hotter from the element, but the convection we saw in the boiling water is circulating to help the snow melt faster. Remember that convection it is the transfer of heat through the movement of particles; warm particles rise, cool particles fill in the space below.
The convection will continue until the liquid water boils and becomes steam unless we put a heavy lid on the pot. If the lid is heavy enough and seals the pot so that no steam can escape, there is too much pressure for the water to boil, and the liquid water can be hotter than 212°F. The opposite occurs when the pressure is low. At high altitudes, water boils at a lower temperature.
We will look at temperature, pressure and moisture a lot closer in the next section.
For now, just keep in mind that everything we see as weather exists because of three things, heat energy from the Sun, air moving because of temperature differences, and more or less moisture in the air because of temperature and pressure.
Review Quiz:
Q1: What provides the heat energy that drives weather?
Q2: What causes the air in the atmosphere to move?
Q3: What are the three physical states of water?
Q4: What are the three basic elements of weather?
Q5: What provides the heat energy that drives weather?
Answers:
A1: The Sun
A2: Differences in temperature cause the air to move. Warm air tends to rise and cooler air that sinks rushes in to replace it.
A3: Solid ice, liquid water and gaseous vapor.
A4: Heat from the sun, temperature differences in the atmosphere, and moisture in the air.
