Climate Continued

Layers of the Atmosphere The atmosphere has 4 distinct layers, each with a particular set of properties.The atmosphere has 4 distinct layers, each with a particular set of properties. Layers are:Layers are: –divided by temperature patterns; –vary in thickness; –are separated by interfaces with names ending in “pause”.

Layers of the Atmosphere The 4 layers of the atmosphere are:The 4 layers of the atmosphere are: –Thermosphere mesopausemesopause –Mesosphere stratopausestratopause –Stratosphere tropopausetropopause –Troposphere

Troposphere Closest to the surface of the Earth Temperature drops as you rise (6.4 o C/km) Composition is 78% nitrogen, 20% oxygen, 2% other gases (Ar,CO 2,Ne,He) Contains most of the dust and water vapor Most weather occurs in this layer

Tropopause

Stratosphere Layer above troposphere Temperature rises as you rise Very little weather

Stratopause

Mesosphere Layer above the stratosphere Temperature drops (to -90 o C) as you rise

Mesosphere Clouds

Mesopause Located where the temperature stops falling in the mesosphere.

Thermosphere The outer, upper layer of the atmosphere Temperatures rise to 1000 o C as you rise Very little matter in this layer High temperatures due to x-rays and UV

Atmosphere Affects Insolation Absorption: the stratosphere absorbs most of the ultraviolet radiation while carbon dioxide and water vapor in the troposphere absorb most of the infrared radiation. Reflection: clouds reflect approximately 25% of incoming insolation.

Atmosphere Affects Insolation Scatteringaerosolswater droplets, ice crystals, pollutants and dustScattering: aerosols (water droplets, ice crystals, pollutants and dust) in the atmosphere cause random reflection of insolation. This scattering of insolation increases as levels of aerosols increases. As scattering increases insolation to the surface decreases. –Ex: volcanic eruptions increase aerosols and greatly reduce insolation to the surface.

Atmosphere Affects Insolation Energy conversion latent heatEnergy conversion: some energy is converted to potential energy (latent heat) by the evaporation of water and the melting of ice and snow. This reduces the amount of energy available to heat an area and also increases the amount of water vapor in the air which also reduces the insolation available making for lower temperatures. Energy is also radiated back into space in the form of heatinfraredEnergy is also radiated back into space in the form of heat (infrared).

Surfaces Land surfaces heat up and cool down more rapidly than water surfaces. Since good absorbers are also good radiators, the land radiates heat to the air above more rapidly than water does. –S–So air above the land heats and cools more quickly than air over water.

Terrestrial Radiation Terrestrial radiationTerrestrial radiation is electromagnetic energy given off by the Earth’s surface. infrared radiation –This is in the form of infrared radiation.

The Greenhouse Effect greenhouse effectThe process that allows short-wave energy to be transmitted through the atmosphere, but which reflects and captures reradiated long wave infrared energy is known as the greenhouse effect.

Radiative Balance vs. Time Radiative balance occurs when the incoming energy equals the outgoing energy. Over long-term periods the Earth seems to be in radiative balance Over short-term periods the Earth does not seem to be in radiative balance.

The Water Budget EvapotranspirationEvapotranspiration refers to all the moisture released into the atmosphere by both evaporation and transpiration. water budgetA water budget is a monthly account of what happens to all the water in a particular location over the course of a year.

Water Budget Income and Expenses Income precipitation“Income” in a water budget is the amount of precipitation. Expenses potential evapotranspiration“Expenses” in a water budget is the potential evapotranspiration. –Potential evapotranspiration wouldif available –Potential evapotranspiration is the amount of water that would evaporate or transpire if the water were available. Therefore potential evapotranspiration is highest in the summer (when it is hottest), lowest in winter (when it is coldest). Large vegetated areas give off more evapotranspiration.

Factors Affecting Water Budgets Climate affects a water budget: since evapotranspiration rates are largely dependent upon the sun, the factors determining climate (temperature and humidity) also affect water budgets. –A–A–A–Arid climate = total annual p pp precipitation is less than potential evapotranspiration. –H–H–H–Humid climate = total p pp precipitation is more than potential evapotranspiration.

Stream Discharge Stream dischargeStream discharge is the amount of water passing a given point in a stream during a given time. –Areas with surplus moisture usually have large amounts of runoff into streams. –Greater amounts of runoff means greater stream discharge. drydeficit base flow –During dry, or deficit, periods when runoff diminishes, streams take water from the ground water supply: this is called base flow.