Our weather is changing. You might have noticed hotter summers and colder winters.
You might have even seen a rising number of major wildfire events, like the Canadian wildfire smoke that swept parts of the eastern United States.
But what causes changes in weather? And how does climate and weather change impact our planet? Read on to learn more.
Greenhouse Gas Emissions
Greenhouse gases naturally exist in the Earth’s atmosphere. These include carbon dioxide, methane, nitrous oxide, water vapor, and fluorinated gases.
However, human activities have massively increased the concentration of these gases. These activities include fossil fuel burning, industrial and agricultural activities, transportation, synthetic chemical usage, mining, and much more.
This amplifies the greenhouse effect, trapping more heat and leading to global warming.
The increased greenhouse gas concentration causes the Earth’s surface and lower atmosphere to warm up. This rise in temperatures affects weather patterns. It makes extreme heat events more frequent and intense.
Global warming alters atmospheric circulation and moisture patterns. That can lead to changes in precipitation.
Some areas may experience increased rainfall and flooding. Others may face reduced rainfall and droughts. Extreme rain and precipitation events are becoming more common in our warming climate.
Warmer ocean waters fuel tropical storms, hurricanes, and cyclones, leading to an increase in their intensity and frequency. Rising sea levels also contribute to storm surges. This then causes more extensive damage to coastal areas during severe weather events.
Deforestation
Deforestation and changes in land use alter the Earth’s surface. This affects the balance of energy and moisture in the atmosphere. Trees and plants absorb carbon dioxide. That helps regulate local and regional climates. Their removal disrupts this balance, contributing to climate change.
Trees play a big role in the water cycle by absorbing water through their roots and releasing it into the atmosphere through a process called transpiration.
They also provide shade, reducing evaporation from the soil. Deforestation disrupts this process, reducing evapotranspiration rates. As a result, the local air becomes drier. That affects humidity levels and potentially alters precipitation patterns.
Trees provide shade and help cool the surrounding environment through a process called evapotranspiration cooling. When forests are cleared, especially in tropical regions, the loss of this cooling effect can lead to higher local temperatures.
These changes in temperature can influence local weather patterns. They can trigger heatwaves.
Forests can modify wind patterns due to the friction between trees and the wind. Deforestation disrupts these wind patterns, potentially altering local wind directions and speeds.
Wind pattern changes can influence the movement of air masses. That affects weather systems in the region.
Trees release moisture into the atmosphere through transpiration. Deforestation leads to a reduction in atmospheric moisture, affecting humidity levels. This reduction in moisture can influence cloud formation, precipitation, and weather patterns.
Solar Radiation
Solar radiation provides the energy that powers the Earth’s climate system. Sunlight warms the Earth’s surface. This creates temperature gradients that drive atmospheric circulation and weather patterns.
Regions near the equator receive more direct sunlight, leading to warmer temperatures. Polar regions receive less direct sunlight and are cooler.
Solar radiation plays a role in cloud formation. When the sun heats the Earth’s surface, warm, moist air rises and cools. Then, it condenses and eventually forms clouds. Clouds impact weather by influencing temperature, precipitation, and atmospheric stability.
Although natural changes in solar output have historically impacted climate, current climate change is primarily driven by human activities.
Solar heating influences the stability of the atmosphere. The heating of the Earth’s surface by solar radiation can cause the air to rise. That creates unstable conditions that lead to the formation of clouds, thunderstorms, and other weather events.
Solar radiation heats land and water bodies differently. That can lead to contrasting temperature patterns and contribute to localized weather phenomena. These can include things like sea breezes, land breezes, and monsoons.
Solar heating influences the stability of the atmosphere. The heating of the Earth’s surface by solar radiation can cause the air to rise, creating unstable conditions that lead to the formation of clouds, thunderstorms, and other weather events.
Natural Variability
Natural climate variability can cause short-term fluctuations in weather and climate.
Ocean currents and oscillations influence weather patterns. These could include things like El Niño-Southern Oscillation, Pacific Decadal Oscillation, and Atlantic Multidecadal Oscillation. ENSO, for example, involves the periodic warming (El Niño) and cooling (La Niña) of the central and eastern tropical Pacific Ocean.
Lunar phases, including the moon’s gravitational pull, can influence ocean tides and, to a lesser extent, atmospheric pressure. These lunar-induced variations can affect localized weather patterns. This can be particularly pronounced in coastal areas.
Interactions between the land surface and the atmosphere, such as land use changes, vegetation dynamics, and soil moisture variations, can influence weather patterns regionally by altering energy and moisture exchanges.
Atmospheric Pressure
Pressure is the atmospheric force exerted in a given area. High-pressure systems involve descending air, resulting in stable, clear weather. The air diverges and sinks, suppressing cloud formation.
Low-pressure systems witness rising air, leading to cloud development and potential precipitation. The convergence of air into a low-pressure area sets off atmospheric instability and often results in stormy weather.
The pressure gradient, indicated by isobars on weather maps, guides wind patterns. When isobars are tightly packed, a steep pressure gradient forms, generating strong winds.
Widely spaced isobars signify a weaker gradient and calmer winds. Understanding pressure gradients helps forecasters anticipate wind strength and its impact on weather conditions.
Circulation
Global circulation cells, propelled by solar heating and the Earth’s rotation, shape weather on a larger scale. Hadley, Ferrel, and Polar cells dictate prevailing wind directions and patterns.
The Hadley cell, closest to the equator, brings warm, moist air that leads to convection and the development of tropical storms and rain.
The Coriolis effect, resulting from the Earth’s rotation, deflects moving air, steering prevailing winds. Trade winds and westerlies are prominent wind belts, influencing weather in specific regions.
Trade winds, moving from east to west, converge near the equator, fostering convective activity and the intertropical convergence zone. Westerlies, by contrast, guide mid-latitude weather patterns.
Jet streams-high-altitude fast-flowing wind belts-influence weather systems and storm tracks. Polar and subtropical jet streams significantly impact the intensity and direction of weather systems, including storms and precipitation patterns.
On a more local scale, geographic features like mountains, bodies of water, and urban areas influence wind patterns, causing localized weather variations. Coastal areas experience sea breezes due to land-sea temperature differences, while mountains can trigger orographic lifting, altering precipitation patterns.
Volcanic Eruptions and Aerosols
Volcanic eruptions can cause short-term and long-term changes in weather and climate due to the release of various gases and particles, known as aerosols, into the atmosphere.
These eruptions release a variety of materials into the atmosphere, including volcanic gases (e.g., sulfur dioxide, carbon dioxide), water vapor, and solid particles. Solid particles can include things like ash, dust, and sulfur compounds.
Aerosols can scatter and absorb incoming radiation from the sun, preventing a portion of sunlight from reaching the Earth’s surface. This can lead to a temporary cooling effect, known as “volcanic cooling” or “volcanic winter,” in the vicinity of the eruption.
It can even cause problems on a global scale, depending on the size and intensity of the eruption.
Sulfur dioxide emitted during volcanic eruptions can react with atmospheric moisture to form sulfate aerosols.
These aerosols can linger in the atmosphere for an extended period, reflecting sunlight and causing a cooling effect by reducing the amount of solar radiation reaching the Earth’s surface.
Volcanic aerosols can alter weather patterns by influencing the distribution of solar energy in the atmosphere. Changes in solar radiation can affect atmospheric circulation, altering wind patterns, temperature gradients, and precipitation patterns.
They can create volcanic clouds. These clouds can induce changes in precipitation by acting as ice nuclei, encouraging cloud droplets to form, and potentially enhancing precipitation, particularly in regions downwind of the eruption.
These eruptions can inject aerosols and gases into the stratosphere, where they can persist for a long time, sometimes years. This can lead to a prolonged cooling effect on global temperatures and alterations in climate patterns.
Urbanization
Urbanization is a significant driver of changes in local weather patterns and can have broader impacts on climate.
Commonly used urban materials like asphalt and concrete absorb and retain heat. That causes elevated temperatures. This effect can influence local weather patterns and exacerbate heatwaves.
Urban areas often retain heat, even during the night. The absorbed heat from the day is slowly released during the night, leading to warmer nighttime temperatures compared to rural areas.
Urbanization affects water bodies and hydrological cycles. Changes in land use can lead to alterations in runoff patterns, increased flooding, and changes in streamflow, all of which impact local weather and climate.
It’s associated with increased air pollution due to industrial and vehicular emissions. This pollution can influence cloud formation, precipitation, and air quality, impacting local weather.
Heat Islands
Urban heat islands refer to localized areas within cities or metropolitan areas where temperatures are significantly higher than the surrounding rural areas.
Urban surfaces have a lower albedo (reflectivity) compared to natural landscapes. Dark surfaces like asphalt and roofs absorb more solar radiation, leading to higher surface temperatures. This absorbed heat is then re-radiated as longwave infrared radiation, contributing to warming in the immediate surroundings.
Urbanization often involves the removal of vegetation. Trees and greenery help cool the air through shading and the release of moisture into the atmosphere. The loss of vegetation in urban areas exacerbates the heat island effect.
Urban heat islands create distinct microclimates within cities, influencing temperature, humidity, and wind patterns. These microclimates can affect how weather systems move and evolve within urban areas.
Ocean Circulation
Ocean currents help distribute heat around the Earth. Warm ocean currents transfer heat from the tropics towards higher latitudes, warming coastal areas and influencing the temperature and climate of nearby landmasses. Cold ocean currents have a cooling effect on adjacent coastal regions.
The interaction between the ocean and the atmosphere influences the characteristics of air masses. Air masses that pass over the ocean can gain or lose moisture and heat, which affects their properties and subsequently the weather they bring to nearby land areas.
Cold ocean currents can lead to fog formation. When cold ocean currents come into contact with warm, moist air from the land, the temperature difference causes the air to cool rapidly, resulting in the formation of fog.
Ocean heat is a primary energy source for the formation and intensification of tropical cyclones. Warm ocean waters provide the necessary heat and moisture for these intense weather systems to develop and strengthen.
Cold and Warm Fronts
Cold and warm fronts are boundary zones between air masses with different temperature, humidity, and density characteristics. The interaction of these air masses often results in significant changes in weather.
Warm Fronts
A warm front happens when a warm air mass advances and rises over a retreating cold air mass. As the warm air rises, it cools, and clouds form in the process. The rising warm air can lift for an extended period, creating widespread cloud cover.
Warm, moist air rising over the denser, cooler air creates various cloud types like stratus, nimbostratus, and altostratus. This often leads to prolonged periods of precipitation, such as steady rain or drizzle, as the moist air condenses.
The warm front’s gradual, gentle slope means that the lifting process occurs over a broader area, resulting in extended periods of light to moderate precipitation.
As the warm front passes, temperatures typically rise, and humidity increases. However, the increase may not be sudden or drastic, as warm fronts have a more gradual influence on weather compared to cold fronts.
Following the passage of a warm front, overcast skies and light, steady precipitation may persist for a day or more. Eventually, as the warm air mass completely replaces the cold air, skies may clear, and the weather becomes warmer and more stable.
Cold Fronts
A cold front occurs when a cold, dense air mass advances and displaces a warm air mass. Cold air is denser, so it undercuts warmer air, forcing it to rise rapidly.
The cold, dense air forces the warm air to rise rapidly, leading to the formation of towering cumulonimbus clouds and often resulting in intense thunderstorms.
Cold fronts are typically associated with abrupt, intense precipitation, often in the form of heavy rain, thunderstorms, or, in colder climates, snow showers.
Ahead of a cold front, temperatures are warmer and humidity is higher. Behind the front, temperatures drop quickly, and the air becomes drier due to the influx of the colder air mass.
Following the passage of a cold front, skies usually clear and the weather becomes cooler and more stable. In some cases, gusty winds may persist, especially in the wake of strong cold fronts.
Topography and Land-Sea Contrasts
Topography, the varying physical features of the Earth’s surface, profoundly influences weather patterns due to its ability to alter air movement and atmospheric conditions.
One key effect is orographic lifting, where air is forced to ascend when it encounters elevated landforms like mountains.
As the air rises, it cools and condenses, leading to cloud formation and precipitation on the windward side of the mountain.
The leeward side experiences a rain shadow effect, characterized by descending air, creating a drier climate due to reduced moisture.
Additionally, temperature variations due to topography are also a factor. Higher altitudes, such as mountainous regions, generally experience cooler temperatures due to the decrease in air pressure and temperature with elevation.
Valleys and lowlands, on the other hand, may exhibit different temperature patterns influenced by surrounding topographical features.
In the case of land-sea contrasts, the differing thermal properties of land and water significantly impact weather.
During the day, land heats up and cools down more rapidly than water. This creates pressure differences, resulting in sea breezes during the day, where cool, moist air from the sea moves inland to replace the rising warm air over the land.
At night, the land cools faster than the sea, generating land breezes as air moves from the land to the sea.
Moisture availability is another critical factor influenced by land-sea contrasts. Oceans act as vast reservoirs of moisture, and winds carry this moisture over the land, leading to cloud formation and precipitation.
Coastal areas often experience a maritime influence on climate, characterized by milder and more stable temperatures due to the ocean’s moderating effect, providing valuable insights into the local weather.
Consequences of Weather Changes
While slow changes in weather might not seem like a big deal, there are massive consequences for our planet.
More frequent and intense extreme weather events, such as hurricanes, heatwaves, floods, droughts, and storms, can cause widespread damage to infrastructure, disrupt communities, and result in loss of life and property.
Changes in weather patterns, influenced by climate change, contribute to rising sea levels. This threatens coastal communities with increased flooding, loss of land, and salinization of freshwater sources
Weather pattern changes, especially extreme heat, can pose significant health risks. These could include heat-related illnesses, respiratory problems due to air pollution, and the spread of diseases carried by insects or animals.
Extreme weather events and changing weather patterns can have substantial economic impacts. These events can increase insurance costs.
They can disrupt supply chains. All of this can lead to decreased productivity in affected regions.
Weather changes impact energy production and distribution. For instance, extreme weather events can damage power infrastructure, disrupt energy supplies, and affect energy demand due to heating or cooling needs.
Communities might be forced to migrate or adapt as a result of extreme weather. This can lead to social displacement, conflicts over resources, and challenges in finding sustainable living conditions.
Changes in weather patterns can strain existing infrastructure, making it more vulnerable to damage. Aging infrastructure may not be adequately prepared for the increasing frequency and intensity of extreme weather events.
To learn more about the consequences of climate change, listen to A Climate Change.
Preventing Changes in Weather
Changes in weather due to climate change isn’t necessarily a lost cause. There are ways the tide can be reversed.
Mitigation efforts are aimed at reducing the greenhouse gas emissions responsible for climate change. Transitioning to renewable and clean energy sources, enhancing energy efficiency, and implementing carbon capture technologies are key strategies.
Sustainable transportation, responsible land use, forest conservation, waste management, and educating individuals on sustainable practices contribute to these efforts.
By collectively reducing emissions and adopting sustainable practices, we can mitigate the human-induced influences on climate and subsequently on weather patterns.
Adaptation is equally crucial. Building climate resilience through robust infrastructure and efficient water management, along with developing early warning systems, are essential steps.
Raising Awareness
Educating yourself and others is a great way to learn more about fighting climate change. Check out these podcasts to learn more about different aspects of climate change.
Once you’ve educated yourself, you can help raise awareness about these issues. Share the resources and content you’ve consumed with others.
Support and advocate for policies that promote sustainability, renewable energy, conservation, and climate action at local, regional, and national levels.
Participate in or initiate community projects focused on sustainability, environmental awareness, and climate action. Collaborate with local organizations and community members to work towards making change.
Encourage schools and educational institutions to include climate change education in their curricula. Support programs that promote climate literacy and understanding among students.
You can also use social media platforms to share information about climate change, weather impacts, and sustainable practices. Amplify messages and initiatives related to climate action.
Donate to or volunteer with climate-focused organizations working to combat climate change, protect the environment, and raise awareness.
What Causes Changes in Weather? Now You Know
What causes changes in weather? There are a lot of different things. But the biggest driver of weather changes leads back to climate change.
Are you ready to learn more about climate change? Check out A Climate Change with Matt Mattern on Apple Podcasts, Spotify, and iHeart Radio.