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Weather... You cant see me, but you feel me, you cant touch me, but I can touch you. I have been called the Breathe of the Gods, or the killer and giver.

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Presentation on theme: "Weather... You cant see me, but you feel me, you cant touch me, but I can touch you. I have been called the Breathe of the Gods, or the killer and giver."— Presentation transcript:

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3 Weather... You cant see me, but you feel me, you cant touch me, but I can touch you. I have been called the Breathe of the Gods, or the killer and giver of life, gentle and fierce, friendly and enemy, angry and happy. The Native Americans called me Moriah, and Snow Eater (Chinook). The Japanese call me Kaze and in Russia I am called Veter. I can shatter homes, or wake a child from a peaceful sleep or bring relief in times of need. I can spread the most dreaded diseases or bring a welcome freshness. What am I?

4 Weather is.... The current state of the atmosphere...what is happening right now BUT… Climate is different Climate – longer time scale (the average conditions, temperature, humidity, rainfall, winds, and other meteorological elements over a long period of time

5 Main points to remember as we learn about weather: The sun warms the earths surface and therefore all the air above the surface The earth is warmed most at the equator and least at the poles---why? The air above land is warmed more quickly than air above water. Warm air expands and rises, creating an area of low pressure; cold air is dense and sinks, creating an area of high pressure

6 What are weather variables? Temperature Temperature Barometric (air) pressure Barometric (air) pressure Wind speed/ Wind Direction Wind speed/ Wind Direction Humidity (Relative humidity) Humidity (Relative humidity) Precipitation Precipitation

7 The Station Model The Station Model

8 Weather Factors Weather: The state of the atmosphere at a specific time and place TEMPERATURE= the average motion of molecules TEMP= movement of molecules= feels hot TEMP= movement of molecules= feels cold

9 Instruments to measure weather variables Temperature Temperature Measured with a thermometer Measured with a thermometer 2 common scales are Farenheit*** and Celcius 2 common scales are Farenheit*** and Celcius

10 Air Pressure- the force exerted by a column of air at a given point Warm air= expanding or rising air= leaves behind L pressure Cold Air=sinking air= leaves an area of H pressure The higher the altitude… the lower the pressure

11 Air Pressure Air pressure (H or L) is measured with a device called a barometer Air pressure (H or L) is measured with a device called a barometer Units of pressure: millibars and inches of mercury

12 Air pressure rules When air pressure is noted on station model as greater than 500, we place a 9 in front of the number and a decimal point at the tenths place. Ex 506 = 950.6 mB of air pressure When air pressure is noted on station model as greater than 500, we place a 9 in front of the number and a decimal point at the tenths place. Ex 506 = 950.6 mB of air pressure When the air pressure is noted as less than 500, we place a 10 in front of the number and a decimal at the tenths place Ex 467 = 1046.7 mB of air pressure When the air pressure is noted as less than 500, we place a 10 in front of the number and a decimal at the tenths place Ex 467 = 1046.7 mB of air pressure

13 Trends in Atmospheric Pressure If the pressure is falling… stormy weather lies ahead If the pressure is falling… stormy weather lies ahead If the pressure is rising… clear skies are coming If the pressure is rising… clear skies are coming

14 Wind -moving air Direction and speed are needed to describe the wind Wind direction is the direction that wind is blowing from Wind moves from High Pressure to Low Pressure Large pressure gradient= strong winds The knot is a unit of speed equal to one nautical mile per hour, which is equal to exactly 1.852 km/h and approximately 1.151 mph The knot is a unit of speed equal to one nautical mile per hour, which is equal to exactly 1.852 km/h and approximately 1.151 mphspeednautical milespeednautical mile

15 What causes winds? A wind is a horizontal movement of air from a area of high pressure to an area of low pressure A wind is a horizontal movement of air from a area of high pressure to an area of low pressure It is this difference in pressure that makes the air move=wind It is this difference in pressure that makes the air move=wind Winds are measured by direction and speed The anemometer is the tool we use to measure this Wind chill= cooling the wind causes

16 Wind speed Wind speed is measured using an anemometer. Speed is measured in mph or knots (1.15 mph = 1 knot) Wind speed is measured using an anemometer. Speed is measured in mph or knots (1.15 mph = 1 knot) Feathers are used to show wind speed on a station model Feathers are used to show wind speed on a station model

17 Wind direction Wind direction is found by using a wind vane. Wind direction is found by using a wind vane. Wind direction is always described as the direction FROM which the wind moved Wind direction is always described as the direction FROM which the wind moved

18 Local Winds The land cools and heats faster than the ocean. Water holds heat longer than land, and takes longer to heat or cool. SEA BREEZE During the day, the land gets hotter faster than the water. The heated air rises, leaving behind an area of low pressure. Wind from the cooler sea blows in to take the place of that warmer air. These happen during the day!

19 Land Breezes At night the lands cools off faster than the sea. Cool air sinks creating an area of high pressure. Wind blows from the land to the sea.

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21 Wind Speed and Isobars Isobars- Isolines of equal pressure The larger the pressure gradient the faster the The closer the isobars the faster the wind

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23 Coriolis deflects winds to the right in the northern hemisphere

24 Wind speed (cont)

25 Draw the tail feather on a station model A. A 5 knot wind blows from the N A. A 5 knot wind blows from the N B. A 10 knot wind blows from the N B. A 10 knot wind blows from the N C. A 15 wind blows from the N C. A 15 wind blows from the N D. A 20 knot wind blows from the N D. A 20 knot wind blows from the N E. A 30 knot wind blows from the N E. A 30 knot wind blows from the N F. A 35 Knot wind blows from the N F. A 35 Knot wind blows from the N G. Repeat A-F for a Southerly Wind, a North Easterly Wind and a South Westerly Wind G. Repeat A-F for a Southerly Wind, a North Easterly Wind and a South Westerly Wind

26 Humidity -the amount of water vapor in the air (mass of water vapor/total mass of air) The hotter the air… the more water vapor it can hold

27 Relative Humidity -the amount of water vapor in the air compared to what the air can hold (before the air is saturated) Relative humidity is defined as the ratio of the water vapor compared to the amount of water vapor that the water could hold. Relative humidity is expressed as a percentage Relative humidity is defined as the ratio of the water vapor compared to the amount of water vapor that the water could hold. Relative humidity is expressed as a percentage High relative humidity= muggy feel or rain

28 Relative Humidity Relative humidity is described as the amount of water vapor in the air compared to the total it can hold. (ex. sponge) Relative humidity is described as the amount of water vapor in the air compared to the total it can hold. (ex. sponge) Measured with a sling psychrometer Measured with a sling psychrometer

29 Relative Humidity -the amount of water vapor in the air compared to what it could hold Dry air= 0% Saturated = 100% The hotter the air… the more water vapor it can hold

30 Dew Point -the temperature at which water vapor condenses out of the air - the temperature at which air is saturated Dew in the moring The hotter the air… the more water vapor it can hold

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32 Dry air is more dense than moist air Humid air is less dense than dry air because a molecule of water (mass =1+1+16 18 ) is less massive than a molecule of nitrogen (mass= 14 +14 28) and a molecule of oxygen (16+16 32). Humid air is less dense than dry air because a molecule of water (mass =1+1+16 18 ) is less massive than a molecule of nitrogen (mass= 14 +14 28) and a molecule of oxygen (16+16 32).nitrogenoxygennitrogenoxygen Pressure and Moisture also have an inverse relationship

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34 Review As altitude, temperature and moisture increases, density and pressure decrease As altitude, temperature and moisture increases, density and pressure decrease

35 Cloud Formation Clouds form when water vapor condenses on aerosols (dust, salt particles in the air) Factors needed for cloud formation… The temperature in which condensation begins is called the dew point

36 TYPES OF CLOUDS Cirrus Clouds: wispy, feathery clouds Form only at high levels, therefore are made of ice crystals

37 Types of Clouds Cumulus Clouds: are puffy white cotton ball looking clouds

38 Cumulonimbus Clouds These are thunderstorm clouds

39 Types of Clouds Stratus Clouds: clouds that form in flat layers- cover all or most of the sky and are low level clouds

40 Precipitation FALLING LIQUID OR SOLID WATER FROM CLOUDS (RAIN, DRIZZLE, SNOW, SLEET FREEZING RAIN, HAIL) FALLING LIQUID OR SOLID WATER FROM CLOUDS (RAIN, DRIZZLE, SNOW, SLEET FREEZING RAIN, HAIL)

41 Precipitation A rain gauge is used to measure the amount of precipitation over a period of time A rain gauge is used to measure the amount of precipitation over a period of time

42 Types of precipitation Rain- Falls from clouds above Freezing and air above freezing Rain- Falls from clouds above Freezing and air above freezing Drizzle- Small precipitation <0.5 mm Drizzle- Small precipitation <0.5 mm Snow- Falls from clouds below freezing and air below freezing Snow- Falls from clouds below freezing and air below freezing Sleet- Falls from clouds above freezing but air below freezing Sleet- Falls from clouds above freezing but air below freezing Hail-up and down movement of rain in clouds multiple freezing as altitude goes up and down Hail-up and down movement of rain in clouds multiple freezing as altitude goes up and down Freezing Rain-Hail-Falls from clouds and air above freezing but ground below freezing Freezing Rain-Hail-Falls from clouds and air above freezing but ground below freezing

43 Haze, Fog and Smog are NOT forms of PRECIPICATION

44 Problem Set 3 Identify the forms of precipiation Identify the forms of precipiation

45 Reading a weather map ISOBAR= connects areas of equal pressure BAR comes from BARometric pressure

46 Reading a weather map... Isotherm: Connects areas of equal temperature; therm means temperature

47 Aim Masses &Source Regions Air Mass is an extremely large body of air whose properties of temperature and moisture content (humidity), at any given altitude, are fairly similar in any horizontal direction. Source Regions are simply geographic areas where an air mass originates. Should be: uniform surface composition - flat light surface winds

48 Air Mass Classification 4 general air mass classifications categorized according to the source region. polar latitudes P - located poleward of 60 degrees north and south tropical latitudes T - located within about 25 degrees of the equator continental c - located over large land masses--dry marine m - located over the oceans----moist

49 Types of Air Masses cP continental polar cold, dry, stable cT continental tropical hot, dry, stable air aloft--unstable surface air mP maritime polar cool, moist, and unstable mT maritime tropical warm, moist, usually unstable

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52 Air masses are masses of air that have the same characteristics of the surface over which it develops Pressure Systems descending (going down)=H pressure ascending (going up)=L pressure Air Masses

53 FrontsFronts: Fronts: the boundary between 2 air massesFronts Warm Front: warm air slides over departing cold air- large bands of precipitation form This is the symbol on a map for a warm front

54 Cold Fronts Cold air pushes under a warm air mass. Warm air rises quickly=narrow bands of violent storms form This is the symbol for a cold front

55 Occluded Front 2 air masses merge and force warm air between them to rise quickly. Strong winds and heavy precipitation will occur This is the weather map symbol for an occluded front

56 Stationary Front Warm or cold front stops moving. Light wind and precipitation may occur across the front boundary This is the weather map symbol for a stationary front

57 Problem Set What type of weather is associated with each type of front Draw the symbol for each front

58 Wind blows from high pressure areas to low pressure areas

59 The pressure gradient and coriolis force cause lows to spin counter clock-wise and highs to spin clockwise


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