Weather

What is Weather????? Weather Animation

Weather Definition Weather – state or condition of the variables of the atmosphere at a given time Weather variables – temperature, air pressure, wind, moisture, cloud cover, precipitation, storms Weather occurs in the ____________ (lower layer of the atmosphere) ***________________is what drives weather** troposphere Heat energy

Temperature Three Scales: Isotherms – lines that connect Where can we find this table?? Fahrenheit, Celsius, Kelvin equal lines of temperature

Sample Conversion Questions What instrument is used to measure temperature? ____________________________ _____ Question 1. The highest air temperature ever recorded in Albany, NY was 104° F. This temperature is equal to?? 40°C / 313°K A thermometer

Heating the Atmosphere The __________is the original source of almost all the heat in the atmosphere The more the insolation at a location, the warmer ___________________ __________________ Average TemperaturesAverage Temperatures Animation sun Earth’s surface and the atmosphere will be

The ways in which the atmosphere is heated include: Conduction: moves heat from ______________________as air touches Earth’s surface Absorption: 1.Absorption of insolation from the sun by __________________moves heat into atmosphere 2.Absorption of ________________ ________________________moves heat into atmosphere Earth into the atmosphere gases and aerosols infrared radiation given off by Earth’s surface

Example of conduction warming the air

Example of absorption warming the air

The ways in which the atmosphere is heated include: Condensation: The release of large amounts of _____________, which will directly heat the atmosphere This happens when __________________ ___________________ Coriolis Effect: Due to rotation and winds, causes ___________________________ _______________ stored heat clouds, fog, dew, and frost form friction between air and Earth’s surface

How condensation warms the air

Another Important Heat Transfer Convection – Heat is transferred within the atmosphere due to _____________ ___________________ The difference in density causes a ___________________________ The difference in air pressure causes the air to move in circular patterns, which are known as __________________ differences in air density difference in air pressure Displacement of air/water convection currents

Transfer of heat in atmosphere through convection

Expansion and compression When a gas __________, its temperature _______________ (Air rises expands and cools) When a gas ____________, its temperature ____________ (Air sinks compresses and warms) Therefore, air temperature decreases with increasing altitude because the air _______________________ expands decreases compresses increases rises, expands, and cools

Weather Instruments

Thermometer Measures temperature

Anemometer Measures wind speed

Wind Vane Measures wind direction

Barometer Measures air pressure

Rain Gauge Measures rain amount

Psychrometer Measures moisture in the air

Weather Station Models

Weather Models

Weather Station Models: used to describe weather conditions:

Using your reference table: Find Temperature, Dewpoint, Pressure, Pressure Trend, Wind Direction, Wind Speed, Visibility of the model below

Weather Models 2

Do Now: Air rises ___________ and ____________ Air sinks ___________ and ____________ Draw this picture and show what happens to air and show where clouds would form: expandscools compresseswarms

Atmospheric Moisture Exists in ____________________in atmosphere Water enters the atmosphere by: –Evaporation – liquid changes into gas –Transpiration – plants release water vapor –Evapotranspiration – evaporation and transpiration together Remember it’s the _______ that provides the energy for these to occur !!! solid, liquid, and gas sun

The net evaporation rate of water is determined by: 1.Amount of energy: More energy(higher temp)=Faster evaporation 2.Surface area of the water More spread out = Faster evaporation 3.Degree of saturation More saturated = Slower evaporation 4.Wind speed Greater wind speed = Greater evaporation

Humidity Absolute Humidity - - hotter air can hold __________water vapor than cold air Relative humidity – –The one you see in forecasts water vapor in each unit volume of air (or moisture capacity) more ratio of the amount of water vapor in the air to maximum amount it can hold

Which is heavier? Which is heavier dry air or wet air? N2N2 O2O2 vs. N2N2 N2N2 O2O2 H2OH2O H2OH2O O2O2 H ₂ 0 turns out to be a lighter molecule than most of the molecules in the air (0 ₂ and N ₂ vs. H ₂ 0) For a given volume of space DRY AIR IS HEAVIER THAN MOIST AIR because--molecular weight of H2O is 18 molecular weight of nitrogen is 28 DRY AIR IS MOSTLY COMPOSED OF NITROGEN

Would a baseball travel further when it is warm or cold? At a HIGHER HUMIDITY, baseballs will travel a little further, all else being equal. At the same temperature, air with a higher dew point will be less dense. When air WARMS, it expands. This warming and expansion lowers the density of the air. This produces longer flight distances, all else being basically equal.When air WARMS, it expands Would a baseball travel further on a night where the air is saturated or dry?

Dew Point Dew point – **If air temp drops below dew point - Water vapor in the air will condense into liquid water** temperature at which air can no longer hold all of its water vapor, and some of the vapor condenses into liquid water

Dew Point Example: Today we read that the dew point of the air is 44°F; the present temperature is 75°F. This means that if the temperature were to fall to 44°F tonight, water in the air would condense (forming dew). If the temperature were to only fall to say 50°F, no dew would form!

Measuring Moisture Sling Psychrometer – Contains: 1. __________________– ordinary thermometer 2.__________________– thermometer with wet wick around it instrument used to measure relative humidity and dew point dry -bulb thermometer wet-bulb thermometer

To convert relative humidity and dew point You must use page 12 of ref. table 1.Subtract: dry bulb temp – wet bulb 2.Locate dry bulb on left side 3.Locate answer to step 1 on top of chart 4.See where those two numbers meet ****Make sure you are using the correct chart: dew point or relative humidity

Try a couple examples: 1. What is the relative humidity where the dry bulb temperature is equal to 18 o C and a wet bulb temperature of 15 o C? Step 1: 18 o C - 15 o C = 3 o C Step 2: Dry bulb temp = 18 o C Step 3: Locate number from step 1 on top of chart Step 4: Find where two Numbers meet

Try a couple examples: 2. What is the dew point temperature when dry bulb temperature is equal to -4 o C and a wet bulb temperature of -5 o C?

Which weather station model shows the highest relative humidity? Why?

86 converts to converts to converts to converts to converts to converts to converts to converts to Which weather station model shows the highest relative humidity? Why?

86 converts to converts to 25 Difference of 5 72 converts to converts to 19 Difference of 3 57 converts to converts to 10 Difference of 4 77 converts to converts to 24 Difference of Which weather station model shows the highest relative humidity? Why?

Relative Humidity = 66% Relative Humidity = 75% Relative Humidity = 60% Relative Humidity = 92% Which weather station model shows the highest relative humidity? Why?

Cloud Formation 1.Air _________________________ 2.Air reaches ____________________ 3.Water begins to ______________, meaning it will change from a _______ to a ____________ 4.Water droplets form on _______________________ (dust particles / aerosols) rises and cools its dew point condense gas liquid condensation nuclei

Precipitation Precipitation – ___________________________ ___________________________ _____________ In order for precipitation to occur ___________________________ ___________________________ _ so that they will fall under the influence of gravity The falling of liquid or solid water from clouds towards Earth’s surface the ice crystals or water droplets must be big enough

Precipitation occurs when liquid or sold water could particles collide becoming ____________________ Forms of precipitation include: __________________________________ _________________________ heavy enough to fall rain, drizzle, snow, sleet, freezing rain and hail

Precipitation SNOW:______________________________ SLEET: _______________________________ FREEZING RAIN:_________________________________ _____________________ RAIN:_________________________________ Falling ice crystals, below 32°F Rain freezing as it falls, above 32°F Rain freezing on contact with Earth’s surface, above 32°F Falling liquid droplets, above 32°F

Precipitation will often ___________________________ ___________________________ __ remove pollutants that have been emitted into the atmosphere Video: &NR=1&v=nCyhwcs2wog

To convert pressure on a station model You must use page 13 of ESRT If the barometric pressure on a station model reads 196; it is <500 so we add 10 in front and a decimal place BECOMES mb If the barometric pressure on a station model reads 696; it is >500 so we add 9 in front and a decimal place BECOMES mb