Weather and Climate
What's the difference between weather and climate?
Weather is what the forecasters on the TV news predict each day. They tell people about the temperature, cloudiness, humidity, and whether a storm is likely in the next few days. That’s weather! It is the mix of events that happens each day in our atmosphere. Weather is not the same everywhere. It may be hot and sunny in one part of the world, but freezing and snowy in another.
Climate is the average weather in a place over many years. While the weather can change in just a few hours, climate takes hundreds, thousands, even millions of years to change.
Weather is what the forecasters on the TV news predict each day. They tell people about the temperature, cloudiness, humidity, and whether a storm is likely in the next few days. That’s weather! It is the mix of events that happens each day in our atmosphere. Weather is not the same everywhere. It may be hot and sunny in one part of the world, but freezing and snowy in another.
Climate is the average weather in a place over many years. While the weather can change in just a few hours, climate takes hundreds, thousands, even millions of years to change.
Sometimes the climate of a place is described with graphs like this. This graph shows
how temperature usually changes over a year for a particular place on Earth.
Factors affecting weather and climate
how temperature usually changes over a year for a particular place on Earth.
Factors affecting weather and climate
Factors affecting climateLatitude or distance from the equatorTemperatures drop the further an area is from the equator due to the curvature of the earth. In areas closer to the poles, sunlight has a larger area of atmosphere to pass through and the sun is at a lower angle in the sky. As a result, more energy is lost and temperatures are cooler.
In addition, the presence of ice and snow nearer the poles causes a higheralbedo, meaning that more solar energy is reflected, also contributing to the cold.
The effect of the Sun's rays
In addition, the presence of ice and snow nearer the poles causes a higheralbedo, meaning that more solar energy is reflected, also contributing to the cold.
The effect of the Sun's rays
Altitude or height above sea levelLocations at a higher altitude have colder temperatures. Temperature usually decreases by 1°C for every 100 metres in altitude.
Distance from the seaOceans heat up and cool down much more slowly than land. This means that coastal locations tend to be cooler in summer and warmer in winter than places inland at the same latitude and altitude. Glasgow, for example, is at a similar latitude to Moscow, but is much milder in winter because it is nearer to the coast than Moscow..
Ocean currentsBritain has a maritime climate. A warm ocean current called the North Atlantic Drift keeps Britain warmer and wetter than places in continental Europe.
The North Atlantic Drift
Distance from the seaOceans heat up and cool down much more slowly than land. This means that coastal locations tend to be cooler in summer and warmer in winter than places inland at the same latitude and altitude. Glasgow, for example, is at a similar latitude to Moscow, but is much milder in winter because it is nearer to the coast than Moscow..
Ocean currentsBritain has a maritime climate. A warm ocean current called the North Atlantic Drift keeps Britain warmer and wetter than places in continental Europe.
The North Atlantic Drift
Stuff in the Sky!
If you went outside and looked up at the sky right now, what would you see? Blue sky, puffy clouds, raindrops -- there is so much up there! Some of the stuff in the sky can be seen, and some is invisible. Click on the pictures above to learn about air, the Sun, clouds,water, colors, and pollution in the sky!
What Is Air?
The atmosphere surrounding Earth is full of air! The air in our atmosphere is made of molecules of different gases. The most common gases are nitrogen (78%) and oxygen (about 21%). There are other types of air molecules as well, but in very small quantities. Air is important for almost all life on Earth including plants and animals. Plants need gasses from air to do photosynthesis. Animals need to breathe air to get the oxygen they need to survive.
As you move up in altitude through the atmosphere, the concentration of air molecules decreases. Some people call this "thin air". The air is thinner higher in the atmosphere because there is lower pressure the higher you go up.
There is a special layer of air molecules high in the stratosphere layer of Earth’s atmosphere, called the ozone layer. The composition of the atmosphere is different in the ozone layer. There are more ozone molecules than anywhere else. Ozone molecules help block some of the Sun’s strongest rays. Currently, scientists are monitoring this layer. It has recently become so thin at the South Pole where the molecules are being destroyed that we call it a “hole”.
Layers of the Atmosphere The atmosphere is a protective layer of gasses that surrounds the entire planet. It keeps temperatures within a relatively small range, blocks out harmful rays of sunlight, and provides plants and animals with air to respire. The atmosphere has five different layers that are determined by the changes in temperature that happen with increasing altitude.
If you went outside and looked up at the sky right now, what would you see? Blue sky, puffy clouds, raindrops -- there is so much up there! Some of the stuff in the sky can be seen, and some is invisible. Click on the pictures above to learn about air, the Sun, clouds,water, colors, and pollution in the sky!
What Is Air?
The atmosphere surrounding Earth is full of air! The air in our atmosphere is made of molecules of different gases. The most common gases are nitrogen (78%) and oxygen (about 21%). There are other types of air molecules as well, but in very small quantities. Air is important for almost all life on Earth including plants and animals. Plants need gasses from air to do photosynthesis. Animals need to breathe air to get the oxygen they need to survive.
As you move up in altitude through the atmosphere, the concentration of air molecules decreases. Some people call this "thin air". The air is thinner higher in the atmosphere because there is lower pressure the higher you go up.
There is a special layer of air molecules high in the stratosphere layer of Earth’s atmosphere, called the ozone layer. The composition of the atmosphere is different in the ozone layer. There are more ozone molecules than anywhere else. Ozone molecules help block some of the Sun’s strongest rays. Currently, scientists are monitoring this layer. It has recently become so thin at the South Pole where the molecules are being destroyed that we call it a “hole”.
Layers of the Atmosphere The atmosphere is a protective layer of gasses that surrounds the entire planet. It keeps temperatures within a relatively small range, blocks out harmful rays of sunlight, and provides plants and animals with air to respire. The atmosphere has five different layers that are determined by the changes in temperature that happen with increasing altitude.
Troposphere
The troposphere is where weather happens. The part of this layer that is closest to the Earth is warmer than the top of the layer. The air is heated by the surface of the Earth, which absorbs the Sun’s energy.
Stratosphere
The stratosphere is where jet airplanes fly. Temperatures increase with altitude. The ozone layer within the stratosphere absorbs harmful ultraviolet rays of sunlight.
Mesosphere
Brrr! The coldest parts of our atmosphere are found in the mesosphere. It can reach–90°C up there!
Thermosphere
There are few air molecules is the thermosphere. The thermosphere can heat up to 1,500°C or higher when the Sun is active, making an aurora that lights up the night sky. Astronauts orbiting Earth in the space station or space shuttle spend their time in this layer.
Exosphere
The upper layer of our atmosphere, where atoms and molecules escape into space, is called the exosphere.
Air Pressure
What's a high pressure system?
Sometimes, high in the sky, air slows its forward motion and piles up. This is called convergence. The piled-up air sinks. When the sinking air reaches the Earth’s surface, it spreads out. This is called divergence. In the Northern Hemisphere it spreads out with clockwise surface rotation and is called a high pressure system.
What's a low pressure system?
High in the sky, air moves away from an area faster than air enters an area. When air spreads out (divergence) at high altitudes, air from below flows upward to fill the space, making a low pressure system. The system has surface convergence and anti-clockwise rotation in the Northern Hemisphere
Stable and Unstable Air Weather is strongly affected by how stable or unstable the atmosphere is. Stable air means that the weather is likely to be calm. It may rain or snow slowly and steadily, it may be sunny, but the weather will not change quickly. Unstable air means that the weather might change quickly with very little warning. Unstable air leads to sudden thunderstorms.
What makes the atmosphere stable or unstable? Picture an invisible box of air called an air parcel. If we compare the temperature of this air parcel to the temperature of air surrounding it, we can tell if it is stable (likely to remain in place) or unstable (likely to move). Click below to see the animation of stable and unstable air parcels.
Fronts
What's a Weather Front? An air mass is a large body of air that has similar moisture (density) and temperature characteristics. A front is a transition zone between two air masses.
A cold front is a warm-cold air boundary with the colder air replacing the warmer. As a cold front moves into an area, the heavier cool air pushes under the lighter warm air that it is replacing. The warm air becomes cooler as it rises. If the rising air is humid enough, the water vapor it contains will condense into clouds and precipitation may fall.
As the cold front moves, warm, moist unstable air is usually replaced by cold, dry stable air.
A warm front is the boundary between warm and cool (or cold) air when the warm air is replacing the cold air. Warm air at the surface pushes above the cool air mass, making clouds and storms. Warm fronts often bring stormy weather. Warm fronts often form on the east side of low-pressure systems where warmer air from the south is pushed north.
A warm front typically replaces cool dry air with warm moist air.
The troposphere is where weather happens. The part of this layer that is closest to the Earth is warmer than the top of the layer. The air is heated by the surface of the Earth, which absorbs the Sun’s energy.
Stratosphere
The stratosphere is where jet airplanes fly. Temperatures increase with altitude. The ozone layer within the stratosphere absorbs harmful ultraviolet rays of sunlight.
Mesosphere
Brrr! The coldest parts of our atmosphere are found in the mesosphere. It can reach–90°C up there!
Thermosphere
There are few air molecules is the thermosphere. The thermosphere can heat up to 1,500°C or higher when the Sun is active, making an aurora that lights up the night sky. Astronauts orbiting Earth in the space station or space shuttle spend their time in this layer.
Exosphere
The upper layer of our atmosphere, where atoms and molecules escape into space, is called the exosphere.
Air Pressure
What's a high pressure system?
Sometimes, high in the sky, air slows its forward motion and piles up. This is called convergence. The piled-up air sinks. When the sinking air reaches the Earth’s surface, it spreads out. This is called divergence. In the Northern Hemisphere it spreads out with clockwise surface rotation and is called a high pressure system.
What's a low pressure system?
High in the sky, air moves away from an area faster than air enters an area. When air spreads out (divergence) at high altitudes, air from below flows upward to fill the space, making a low pressure system. The system has surface convergence and anti-clockwise rotation in the Northern Hemisphere
Stable and Unstable Air Weather is strongly affected by how stable or unstable the atmosphere is. Stable air means that the weather is likely to be calm. It may rain or snow slowly and steadily, it may be sunny, but the weather will not change quickly. Unstable air means that the weather might change quickly with very little warning. Unstable air leads to sudden thunderstorms.
What makes the atmosphere stable or unstable? Picture an invisible box of air called an air parcel. If we compare the temperature of this air parcel to the temperature of air surrounding it, we can tell if it is stable (likely to remain in place) or unstable (likely to move). Click below to see the animation of stable and unstable air parcels.
Fronts
What's a Weather Front? An air mass is a large body of air that has similar moisture (density) and temperature characteristics. A front is a transition zone between two air masses.
A cold front is a warm-cold air boundary with the colder air replacing the warmer. As a cold front moves into an area, the heavier cool air pushes under the lighter warm air that it is replacing. The warm air becomes cooler as it rises. If the rising air is humid enough, the water vapor it contains will condense into clouds and precipitation may fall.
As the cold front moves, warm, moist unstable air is usually replaced by cold, dry stable air.
A warm front is the boundary between warm and cool (or cold) air when the warm air is replacing the cold air. Warm air at the surface pushes above the cool air mass, making clouds and storms. Warm fronts often bring stormy weather. Warm fronts often form on the east side of low-pressure systems where warmer air from the south is pushed north.
A warm front typically replaces cool dry air with warm moist air.
Clouds
How Clouds Are Formed
Cooling air that contains water vapor will cause the vapor molecules in the air slow down. As they slow down, some molecules are not able to maintain their vapor form. They cluster (condense) in the air to form tiny liquid droplets. Typically they need some sort of particle, such as dust, to condense upon. These particles are called condensation nuclei.
A cloud is composed of tiny water droplets (or ice crystals) that are suspended in the air. If the droplets become large enough,they may be visible as a cloud or fog.They may also fall to Earth in the form of rain (or snow).
Rainfall
How Clouds Are Formed
Cooling air that contains water vapor will cause the vapor molecules in the air slow down. As they slow down, some molecules are not able to maintain their vapor form. They cluster (condense) in the air to form tiny liquid droplets. Typically they need some sort of particle, such as dust, to condense upon. These particles are called condensation nuclei.
A cloud is composed of tiny water droplets (or ice crystals) that are suspended in the air. If the droplets become large enough,they may be visible as a cloud or fog.They may also fall to Earth in the form of rain (or snow).
Rainfall
Climate graphs
Climate graphs show average rainfall and temperatures typically experienced in a particular location. The temperature is shown on a line graph, and rainfall on a bar graph. They are usually represented on the same set of axes with the months of the year along the base.
Interpreting and describing climate graphs
Climate graphs show average rainfall and temperatures typically experienced in a particular location. The temperature is shown on a line graph, and rainfall on a bar graph. They are usually represented on the same set of axes with the months of the year along the base.
Interpreting and describing climate graphs
- Look at the overall shape of the graph. Is the temperature line steep or gentle? Does it change throughout the year and/or look almost flat?
- Look for extremes - quote the highest and lowest temperature and rainfall and the month in which it occurs. Remember to quote units, eg Celsius or millimetres.
- Can you identify the seasons when most rain or least rain falls? Or when the highest and lowest temperatures are experienced?
- Work out the temperature range by subtracting the lowest figure from the highest figure.
- Add the rainfall totals for each month together to work out the total annual rainfall.
For more on weather and climate check out the resources given below
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