Introduction to Weather & Climate

Introduction to Weather and Climate

  • Date: August 27, 2013

  • Reference: Jason-2 data showing Sea Surface Height Anomaly in millimeters.

Weather vs Climate

  • Weather:

    • Defined as the day-to-day changes in the atmosphere.

    • Influenced by:

    • Precipitation

    • Temperature

    • Wind

    • Cloud cover

  • Climate:

    • Defined as the average weather found in an area, measured over a 30-year period.

    • Represents long-term trends and variations.

Key Goals of the Chapter

  1. Energy Distribution from the Sun:

    • Understand how energy from the sun is spread over the Earth through air and water.

      • Factors influencing weather and climate.

      • Atmospheric circulation.

      • Thermohaline circulation.

  2. Differences in Climate and Landscape Zones:

    • Explore differences between climate zones and biomes.

  3. Geographic Influences on Landscapes:

    • Investigate geographic factors that influence the landscape.

Factors Influencing Climate

  1. Latitude:

    • Affects the intensity of the sun's rays:

      • Sun's rays are distributed unevenly across the Earth's surface due to its tilt and curvature.

  2. Altitude:

    • Refers to height above sea level.

      • At higher altitudes, air density decreases (lighter air).

      • Cold air holds less moisture and heat than warm air.

  3. Distance from the Sea:

    • Large bodies of water moderate coastal climates.

      • Water heats up slower than land and releases heat more gradually leading to:

      • Moderate summers and mild winters in coastal areas.

      • More extreme temperatures in inland areas.

  4. Wind Currents:

    • Wind direction affects temperature and weather conditions; varies between hemispheres.

  5. Ocean Currents:

    • Have a similar effect to wind currents; influenced by water density (cold water sinks, warm water rises).

    • Thermohaline circulation impacts nutrient delivery in oceans.

Consequences of Latitude and Altitude

  • Sun Ray Intensity:

    • Varies with latitude; harsher rays at lower latitudes and more spread out at higher latitudes.

  • Altitude Effects:

    • Higher altitudes lead to lower temperatures and less atmospheric pressure; weather patterns change.

Detailed Discussion of Influencing Factors

Latitude

  • Influence on Temperature:

    • The angle of sunlight hitting the Earth varies causing temperature differences.

    • Tropical areas receive more direct sunlight, while polar areas receive more oblique angles, thus lower temperatures.

Altitude

  • Density Impact:

    • Air density decreases with altitude, affecting weather patterns and climate.

    • Colder air is less capable of holding moisture.

Distance from the Sea

  • Heat Modification by Oceans:

    • Coastal areas experience less temperature fluctuation compared to interior regions due to seawater's heat capacity.

    • Examples include:

    • Coastal regions having milder seasons (e.g., California coast vs. interior deserts).

Wind Currents

  • Dynamics of Temperature Influence:

    • Winds can transport warm air from the tropics or cold air from the poles, affecting local climates.

Ocean Currents

  • Circulation and Climate Links:

    • Interaction of ocean currents with atmospheric conditions shapes climatic patterns globally.

    • Example: The Gulf Stream brings warm water from the tropics toward Europe, moderating its climate.

Köppen Climate Classification System

  • Climate Classification:

    • Developed by German climatologist Wladimir Köppen.

    • Utilizes a three-letter classification system:

    1. First Letter: Main climate type.

    2. Second Letter: Precipitation amounts.

      • Important designations include (f, w, s).

    3. Third Letter: Temperature variations.

  • Major Climate Types:

    • Tropical (A): High temperatures, varying precipitation.

    • Arid (B): Stable low precipitation.

    • Temperate (C): Moderate seasonal temperature and precipitation.

    • Continental (D): Varied seasons and precipitation.

    • Polar (E): Very low temperatures, icy conditions.

Climate Graphs

  • Purpose of Climate Graphs:

    • Illustrates temperature and precipitation patterns over time.

    • Temperature: Represented as a line graph.

    • Precipitation: Represented as a bar chart.

    • Useful for identifying climate types without complex maps.

Global Atmospheric Circulation System

  • Overview:

    • Describes the vast wind system redistributing heat from equatorial regions to the poles.

  • Pressure Zones:

    • Low pressure zones arise from warm air rising.

    • High pressure zones occur when cold air descends, increasing surface pressure.

  • Coriolis Effect:

    • Deflects wind directions in the Northern hemisphere to the right and in the Southern hemisphere to the left.

  • Cells of Air Movement:

    • Hadley Cell: Circulation near the equator, influencing tropics.

    • Ferrell Cell: Mid-latitude effects.

    • Polar Cell: Cold air circulation patterns at the poles.

Monsoons and Seasonal Impacts

  • Intertropical Convergence Zone (ITCZ):

    • A low-pressure zone that shifts with the Earth's tilt, affects annual monsoon cycles, particularly in South Asia.

Conclusion: Climates vs Biomes

  • Climate:

    • Average conditions of temperature and precipitation over 30 years.

  • Biomes:

    • Ecosystems characterized by plant and animal communities, shaped by climate, soil, and geography.

    • Notable similarities exist between the distribution of biomes and climates on Earth.

Introduction to Weather and Climate

The study of weather and climate begins with data such as that from August 27, 2013, which utilized Jason-2 measurements to observe Sea Surface Height Anomalies in millimeters. It is essential to distinguish between weather and climate. Weather describes the day-to-day changes in the atmosphere including fluctuations in precipitation, temperature, wind, and cloud cover. Conversely, climate refers to the average weather conditions found in a specific area measured over a long-term period, typically 30 years. This distinction allows scientists to observe long-term trends and variations rather than just temporary atmospheric events.

Key Goals of the Chapter

This chapter aims to explore how energy from the sun is distributed across the Earth through air and water circulation. This includes a deep dive into atmospheric and thermohaline circulation systems that influence weather and climate globally. Furthermore, the chapter investigates the differences between climate zones and biomes, while also examining the various geographic factors that influence the formation and characteristics of different landscapes.

Factors Influencing Climate

Several physical factors determine the climate of a region. Latitude is a primary influence, as the Earth's tilt and curvature mean the sun's rays are distributed unevenly, hitting tropical areas more directly. Altitude also plays a significant role because air density decreases at higher elevations; this lighter air is colder and holds less moisture than the warmer air found at lower altitudes. The distance from the sea provides a moderating effect on coastal climates because water heats up and cools down more slowly than land. This lead to moderate summers and mild winters in coastal regions, while inland areas experience more extreme temperature ranges.

Global patterns are further shaped by wind and ocean currents. Wind direction varies between hemispheres and significantly affects local temperatures. Ocean currents operate similarly, driven by water density where cold water sinks and warm water rises. This thermohaline circulation is vital for global heat distribution and nutrient delivery. For instance, the Gulf Stream transports warm water from the tropics toward Europe, significantly moderating its climate compared to other regions at the same latitude.

Köppen Climate Classification and Graphs

The Köppen Climate Classification System, developed by Wladimir Köppen, uses a three-letter designation to categorize global climates. The first letter represents the main climate type, such as Tropical (A), Arid (B), Temperate (C), Continental (D), or Polar (E). The second letter indicates precipitation patterns, with common designations like (f, w, s). The third letter specifies temperature variations. To visualize these patterns, scientists use climate graphs. These graphs represent temperature as a line graph and precipitation as a bar chart, providing a clear snapshot of seasonal trends without the need for complex mapping.

Global Atmospheric Circulation and Monsoons

The global atmospheric circulation system acts as a massive heat engine, redistributing thermal energy from the equator toward the poles. This system is defined by pressure zones where warm air rises to create low-pressure areas and cold air descends to form high-pressure zones. The Coriolis effect deflects these wind patterns to the right in the Northern hemisphere and to the left in the Southern hemisphere. Air moves through specific cells: the Hadley Cell near the equator, the Ferrell Cell in the mid-latitudes, and the Polar Cell at the poles. Seasonally, the Intertropical Convergence Zone (ITCZ) shifts with the Earth's tilt, driving the annual monsoon cycles that are particularly impactful in regions like South Asia.

Conclusion: Climates vs Biomes

In summary, while climate represents the average atmospheric conditions over a 30-year period, biomes are the resulting ecosystems characterized by specific plant and animal communities. Biomes are shaped by a combination of climate, geography, and soil. There is a notable correlation between the distribution of climate zones and the distribution of biomes across the Earth's surface, reflecting the foundational role of weather patterns in supporting life.

Weather is defined as the current state of the atmosphere, encompassing phenomena that occur primarily in the troposphere, which is the lowest atmospheric layer. Its key characteristics include temperature, measured in degrees Celsius (^°C), and precipitation, which refers to any form of water such as rain, snow, or hail falling from clouds. Furthermore, weather involves wind, described as the movement of air in terms of direction and speed, and cloud cover, which is the fraction of sky obscured by clouds measured in oktas. Meteorologists use specific instruments for these measurements, including thermometers for temperature, rain gauges for precipitation, and anemometers or wind vanes for wind. Weather is highly dynamic and can change rapidly from moment to moment, such as a sudden shift from sunshine to heavy rain. Observation shows that weather can vary significantly on the same day across different locations, as seen in photographic comparisons between Amsterdam and Groningen.

Temperature

Temperature serves as the quantitative measure of warmth or coldness recorded in degrees Celsius (^°C). Global patterns indicate that the highest temperatures are typically found near the Equator and at lower altitudes, while the lowest temperatures are located at the poles and mountain peaks. To maintain measurement standards, thermometers are housed at heights of 1.25 to 2 meters within Stevenson screens to ensure consistency across the globe. Meteorologists utilize isotherm maps to represent lines of equal temperature. Record extremes include a high of 56.7^°C in Death Valley, USA (1913) and a low of -68^°C in Oymyakon, Russia (1933). For conversion, the formula F = (C \times 1.8) + 32 is used for those utilizing Fahrenheit.

Precipitation

Precipitation includes all wet forms of water falling from the atmosphere, such as rain, snow, and hail, and is measured in millimeters (mm) using rain gauges. It is a vital component of the water cycle, which involves evaporation from liquid to gas and transpiration, where plants release approximately 10\% of atmospheric water. This cycle continues with condensation, where cooling water vapor forms clouds and eventually leads to precipitation. Annual precipitation varies greatly, with De Bilt receiving about 800 mm while Cherrapunji, India, receives as much as 11,777 mm.

Wind

Wind is the movement of air within the atmosphere, with its direction tracked by a compass rose and its speed measured in km/h or mph. The Beaufort scale is commonly used in the Netherlands to assess wind strength, though it is not a universal standard. Wind is generated by differences in atmospheric pressure, moving from high-pressure to low-pressure areas, and is often deflected by the Earth’s rotation via the Coriolis Effect. On weather maps, isobars represent lines of equal atmospheric pressure, where closely spaced lines indicate the presence of strong winds.

Cloud Cover

Cloud cover is an indication of the sky fraction obscured by clouds, measured in oktas. High, feathery clouds known as Cirrus indicate changing weather, while low, lumpy Stratocumulus clouds may or may not bring rain. In contrast, towering Cumulonimbus clouds are associated with thunderstorms and severe weather. Ultimately, weather is characterized as a rapidly changing atmospheric condition influenced by the interplay of temperature, precipitation, wind, and cloud cover.

3.2 The Dutch Climate

Climate differs from weather in that the latter reflects short-term states, while the former represents average atmospheric conditions over typically 30 years. Climate graphs are used to depict these expected conditions over a year, with a horizontal x-axis for months and a double y-axis for temperature and precipitation. In these graphs, temperature (^°C) is shown as a line graph and precipitation (mm) as a bar graph. De Bilt serves as the reference for average Dutch weather, though variations occur between regions like Groningen and Maastricht based on latitude and proximity to water bodies.

Seasonal Influence on Climate

Seasons are caused by the Earth's axial tilt of approximately 23.4^°, which affects the amount of solar radiation different latitudes receive. Plants must adjust their growth and flowering cycles to these changes, which in turn impacts agricultural patterns. A deep understanding of local climates provides necessary insight into agricultural management, weather prediction, and environmental protection.

3.3 Europe’s Climates

Wladimir Köppen developed a climate classification system that categorizes five main climate zones (A-E) based on vegetation needs. The first letter represents the general zone, while the second provides specific climate details. Europe showcases this variability with stark differences in average temperatures between cities like Moscow, Rome, and London, which are influenced by their specific maritime or Mediterranean classifications.

Changes in Climate and Vegetation

Vegetation varies significantly across different climates, ranging from the shrubs and mosses of the tundra to the lush flora of tropical regions. Both altitude and latitude influence these shifts; as one moves further north or higher in elevation, temperature and vegetation types change. The tree line marks the specific elevation or latitude where tree growth can no longer be sustained due to low temperatures.

3.4 Tropical Climates

There are two primary tropical climates: the Tropical Rainforest climate (Af), marked by consistent high temperatures and rainfall, and the Savannah climate (Aw), which has distinct wet and dry seasons. These areas often experience convectional rainfall, occurring when solar energy heats the land and moisture-laden air rises. This process is part of the Hadley Cell circulation, where warm, moist air rising at the equator leads to significant precipitation.

3.5 Arid Climates

Arid climates are characterized by receiving less than 250 mm of rain annually and are typically divided into desert and semi-arid st

eppe climates. These landscapes often feature rocky areas or sand dunes with minimal vegetation. Desert formation is influenced by atmosp,mheric high-pressure zo..nes like Hadley Cells, prevailing wind patterns, and the rain-shadow effect caused by mountains.

3.6 Polar Climates

Polar environments include the Tundra climate (ET), which sees summer temperatures slightly above freezing, and the Ice Cap climate (EF), where temperatures never exceed 0^°C. Life in these regions adjusts through insulation and dietary adaptations suited for extreme cold. However, global warming is significantly impacting these climates, leading to melting permafrost and altered ecosystems.

Initial discussions regarding weather focus on fundamental aspects of the atmosphere, particularly the troposphere, and explore key elements such as temperature, humidity, and wind.