Welcome to Earth Science 2017-2018

Climate Chapter 14

EES News and Notes Today, we’re moving on to climate! After the quiz, we’ll begin our packet work. After that, we’ll move forward through the first section of notes.

Defining Climate Climate is affected by several factors including latitude and elevation

Annual Averages and Variations Climatology: The study of Earth’s climate and the factors that cause past, present and future changes. Climate describes long-term weather patterns of an area; also the annual variations of temp, precipitation, wind and other variables.

Normals Data used to describe an area’s climate are compiled from meteorological records; Includes high and low temps, amounts of rainfall, wind speed + direction, humidity and air pressure. Data are averaged on a monthly basis for 30 years to create normals or standard values of a location.

Limitations of Normals Must use with caution Weather might differ widely from normals on days Most normals are gathered at airports, so weather might differ from the nearby cities since airports are usually outside city limits.

Causes of Climate Climatic variations are largely due to different: latitude topography closeness of bodies of water availability of moisture global wind patterns ocean currents air masses

Latitude Tropics: area between 23.5° S and 23.5° N of the equator. Receive lots of solar radiation Temperate Zones: area between 23.5° and 66.5° N and S of equator. Polar Zones: area north and south of 66.5° to poles.

Topographic Effects Water heats and cools more slowly than air. Coast is warmer in winter and cooler in summer. Temperatures decrease with altitude. Mountain climates are cooler than sea level. Windward side = wet/cool Leeward side = dry/warm

Air Masses Two main causes of weather: Movement + interaction of air masses Avg. weather conditions near air-masses are similar to those exhibited by the air masses themselves.

Climate Classification Climates are categorized according to the average temperature and precipitation amounts

Koppen Classification System A classification system based on the average monthly values of temperature and precipitation. Also considers vegetation. Considers that certain types of plants only grow in certain places, but considers numeric values of temperature and precipitation.

Tropical Climates Year-round high temps In wet areas, up to 600 cm of rain annually Produced tropical rain forests Border areas (transition zones) include wet and dry zones such as savannas (grasslands)

Dry Climates About 30% of Earth’s land area; largest climatic zone World’s deserts (Sahara, Gobi, Australian) Low precipitation, scarce vegetation Near tropics = high solar radiation = high evaporation Arid and semiarid regions

Mild Climates Humid subtropical climates Marine west-coast climates High pressure systems from oceans (SE United States) Warm + muggy summer, cool + dry winters Marine west-coast climates Mild winters and cool summers from sea breeze Mediterranean climates Warm + dry summer, cool + wet winters

Continental Climates Warm summer climates, cool summer climates, subarctic climates Rapid and violent changes in weather Influx of temperatures Summers usually more wet than winters

Microclimates A localized climate that differs the main regional climate. On a mountain or city vs. countryside Heat Islands: Climate is warmer in city than surrounding rural area (asphalt, buildings) Increased cloudiness and rain

Earth’s climate is constantly changing on many different timescales Climatic Changes Earth’s climate is constantly changing on many different timescales

Long-Term Climate Change Glaciers have advanced and retreated over the past 2 million years. Ice Ages: Periods of extended glacial coverage with global temperature decreases. Currently, we’re in between intervals of warmth and cold.

Short-Term Climate Changes Seasons are short term periods with specific weather conditions caused by regular variations in daylight, temperature and weather patterns. Variations based on amount of solar radiation received in areas. Winter in north hemisphere as tilted away from the sun.

El Nino A band of anomalously warm ocean temperatures that occasionally develops off the western coast of SA. Usually, currents pull cold water to SA; during el nino, warm waters move in creating massive storms in some places and droughts in places that are usually wet.

Solar Activity Maunder minimum: describes a period of low sunspots. Corresponds with cold climatic episode Increased solar activity coincides with warmer sea surface temps while low solar activity means colder sea surface temps.

Earth’s Orbit Climatic changes might also be triggered by changes in Earth’s axis and orbit. Elliptical orbit = part of the year is close to sun and, therefore, warmer Circular orbit = further from sun and , therefore, cooler from averages

Earth’s Tilt Earth’s angle is currently 23.5°, but the range is 22.1° to 24.5°. This might change seasons. EX: Low angle means drop in difference between winter and summer (warmer winters and cooler summers) with increased glacial formation.

Earth’s Wobble Over a period of 26,000 years, Earth wobbles as it spins around its orbit. Earth’s axis points towards Polaris currently; it will switch towards Vega in about 13,000 years. More radiation from sun; our summers will become winters and vice versa!

Volcanic Activity Climate change can be triggered by large quantities of aerosols or dust particles. Volcanoes can blow up large enough to block incoming solar radiation and cool the planet! Generally, such volcanic action only has short-term consequences.

Impact of Human Activities Over time, human activities can alter atmospheric conditions enough to influence changes in weather and climate.

The Greenhouse Effect Processes of absorption and radiation of energy in the atmosphere. Natural heating of Earth’s surface caused by certain atmospheric gasses (GHGs). Warms surface by more than 30°C (this allows for life).

The Greenhouse Effect Increasing or decreasing the greenhouse effect is hypothesized to be a matter of atmospheric GHGs Largely, Carbon Dioxide (CO2) and Methane (CH4). Global Warming: A rise in global temp based on increased GHGs in air.

Global Warming Temps have shown upward trend for past 200 years, but higher in recent decades. Polar ice caps and mountain glaciers are melting. Increase in sea level might promote flooding; fertile regions might become arid; increasing sea temp might create more storms.

Burning Fossil Fuels One of the main sources of atmospheric CO2 is from burning coal, oil and natural gas. 98% in USA come from fossil fuels used to run cars, heat homes and run industries. In addition to CO2, other gasses like methane and nitrous oxide are released.

Deforestation Deforestation is the mass removal of trees in a region. Vegetation (like trees) absorb CO2; when we cut down large areas of trees, we cut down the tool that helps regulate CO2 emissions. Scientists agree this intensifies warming trends.

Environmental Efforts Conserving energy is how individuals can reduce the amount of CO2 emitted. Lowering consumption (per person) helps start a trend too! Easy things include turning down thermostats in winter and recycling as well as using cars less frequently!