Module 5: Air Flashcards
Weather
Weather is a local area’s short-term temperature, precipitation, and humidity, wind, speed, cloud cover, and other physical conditions of the lower atmosphere, measured over hours or days.
What is climate?
Climate is an area’s general pattern of atmospheric or weather conditions measure over long periods of time, ranging from decades, to thousands of years.
Weather is not the same as climate. Climate is what we expect, weather is what we get. Climate is usually measured through modelling. Climatologist do climate change. Meteorologist are associate with weather
Climate in Australia
Climate in Australia is hot and dry.
In our longer term weather cycles, we go through extended periods of droughts or wet. This is caused by ocean and wind currents moving around the earth.
What factors influence climate?
Global air circulation Global ocean currents Climate varies mostly due to patterns of global air circulation and ocean currents that distribute heat and precipitation unevenly. Earth's surface features Green house gases
Global air circulation
The air mass moving in particular ways and patterns. Hot air from the equator rises and mov a towards you the poles. Earth’s rotation deflects the movement of air over different parts of the planet, which creates global patterns of prevailing winds (disturbs heat and moisture). This is responsible for the distinct ecosystems that characterise particular regions around the globe.
global ocean currents
The mass movements of water driven by prevailing winds and earth’s rotation that redistribute heat from place to place. Thus, influencing climate and vegetation, especially near coastal areas.
Just like warm air rises, the warm water rises to the top and cold air sinks to the bottom. The heat causes the molecules to become excited and move to the surface, resulting in currents. In the troposphere, the air is moving things around
How are oceans and the atmosphere strongly linked?
- ocean currents are affected by winds in the atmosphere
- heat from the ocean affects atmospheric circulation.
Eg. The El Niño- southern Oscilistion (ENSO) phenomenon - large scale weather event that occurs every few years when prevailing winds in the Pacific Ocean weaken and change direction, which results in above average warming of pacific waters. Alters the weather or 2/3 of the planet to at least 2 years.
What is m The El Niño- southern Oscilistion (ENSO) phenomenon?
The El Niño- southern Oscilistion (ENSO) phenomenon - large scale weather event that occurs every few years when prevailing winds in the Pacific Ocean weaken and change direction, which results in above average warming of pacific waters. Alters the weather or 2/3 of the planet to at least 2 years.
Earth’s surface features
- Heat is absorbed and released more slowly by water than by land: creates land and sea breezes.
- world’s oceans and lakes moderate the weather and climate of land nearby.
- cities create distinct microclimates: bricks, concrete and asphalt absorb and hold heat, while buildings interrupt flows. Cars and air cons real ease heat and pollutants m. Cities tend to have more haze and smog, higher temperatures and lower wind speeds than the surrounding countryside.
Topographic features also create local and regional weather and climate conditions.
E.g. The rain shadow effect is a reduction of rainfall and loss of moisture from the landscape in the side of a mountain facing away from prevailing surface winds. Warm, moist air in onshore winds loses most of its moisture on the windward slopes of a mountain range - this leads to semiarid and arid conditions on the leeward side of the mountain range.
Green house gases
Small amounts of H20 vapour m, CO2, CH4 and N20 influence the earth’s temperatures and climates - one percent of the earth’s troposphere is composed of these green house gases
What is the green house effect?
- Visible light and some UV and IR radiation passes through the atmosphere.
- earth’s surface absorbs much of this radiation and transformed in into IR (heat) which rises into the lower atmosphere.
- some of this heat escapes into space; some is absorbed by molecules of greenhouse gases - it warms lower atmosphere and earth’s surface.
- this natural warming of the troposphere is known as the green house effect.
Without it, earth would be cold and lifeless.
” the heat radiated in the atmosphere by earth earth is absorbed by greenhouse gases like, which cause them to vibrate and release IR into the troposphere
What is the enhanced greenhouse effect?
- human activities are adding greenhouse gases to the atmosphere:
. Burning fossil fuels releases large amounts of CO2
. Growing crops and raising livestock are releasing large amounts of CH4 and N2O
. Clearing CO2 absorbing rainforests faster than they are regenerating. - considerable and growing evidence that these activities are enhancing the natural greenhouse effect and warming the atmosphere, thus changing the earth’s climate.
The enhanced greenhouse effect continued
Humans have been adding more greenhouse gases to the atmosphere e.g fossil fuels, methane, removing vegetation that could take the pollution out of the air as plant use it as photothynthesis to produce oxygen. Holding onto more heat within our troposphere - not the same as the natural greenhouse effect
What are the greenhouse gases?
Carbon dioxide - CO2 methane - CH4 Nitrous oxide - N2O Ozone - O3 Hydrolurocarbons - HFCs
