Weather Part I Revised 2010 Revised 2010 ©Mark Place, 2009-2010 www.LearnEarthScience.com Revised 2010 Revised 2010

In the US, the general direction that weather systems move is toward weather basics Where does the energy for weather originate? the uneven heating of the Earth’s surface In the US, the general direction that weather systems move is toward the northeast

dewpoint are measured in Pressure (see next page) Station Models Use the ESRT Page 13 Cloud Cover Temperature .. 76 138 Wind Direction & Speed -30\ Current Weather 55 Dewpoint Barometric Trend Barometric Pressure Temperature and dewpoint are measured in degrees _______ Pressure (see next page) F

Barometric Pressure 138 Add a decimal between the last two digits 13.8 Add a 9 or 10 in front to fit on the scale (ranges from 950.0 to 1050.0) If under 500 add a 10 If over 500 add a 9 Pressure =1013.8 Click on for Interactive Station Model Practice

Moisture: What Affects Evaporation? Temperature As temperature increases, rate of evaporation increases Direct Relationship Surface Area As surface area increases, rate of evaporation increases Direct Relationship As relative humidity increases, rate of evaporation decreases Relative Humidity Indirect Relationship

What natural process cleans the atmosphere? precipitation Rain Snow Hail

Cloud Formation Cools to the dewpoint Expands Warm Air Rises

Clouds are likely to form when: The air is saturated and rising The temperature is at the dewpoint Condensation nuclei are available

As the Air Temperature Increases, the air can hold more water Sling Psychrometer Used to measure RH & Dew point Dry bulb measures air temperature Wet bulb temp is lower due to evaporation Use dry bulb temp. and wet bulb depression to find DP or RH on chart

Using the charts on page 12 of the ESRTs, calculate the relative humidity and dew point using the following information. Dry Bulb Wet Bulb Difference Dew Point Relative Humidity (%) 14 10 4 20 5 30 19 18 56 6 60 15 12 58 23 7 55 13 5 9 Dewpoint Chart RH Chart

As temperature increases Relative Humidity decreases vs Air Temperature Indirect Relationship Temp. As temperature increases Relative Humidity decreases Amount of moisture in the air RH

As dew point increases the amount of moisture in the air As temperature and dewpoint get closer together, the probability of precipitation INCREASES

Temperature versus Dew point Rain On your study guide circle the area of the diagram where RAIN would occur.

probability of precipitation? Which has the greatest probability of precipitation? Temp.&DP are very close

Pressure and Wind ©Mark Place, 2009-2010 www.LearnEarthScience.com

What instrument is used to measure: wind speed air pressure anemometer barometer [ORIGIN from Greek anemos ‘wind’] [ORIGIN from Greek baros ‘weight’]

The direction in which they come from Differences in Pressure How are winds named? The direction in which they come from What causes wind? Differences in Pressure

Which pressure gradient would result in greater wind velocity?

measurements using the chart Convert the following measurements using the chart on page 13 of the ESRTs. 29.73 997 30.18 994

Wind blows from areas of to areas of high pressure low pressure

Draw the relationship between air pressure and air density.

This is because the air is Therefore, clouds CANNOT form. In a high pressure area, air will (rise, sink) because the air is (less, more) dense. This is because the air is (cold, warm) and (rises, sinks). Therefore, clouds CANNOT form.

This is because the air is In a low pressure area, air will (rise, sink) because the air is (less, more) dense. This is because the air is (cold, warm) and (rises, sinks). Therefore, clouds are LIKELY to form.

Correctly draw the direction of wind flow around both a high and a low pressure area in the NORTHERN HEMISPHERE.

counterclockwise wind direction low pressure high pressure warm or cold air air rising or sinking clouds or no clouds clockwise or counterclockwise wind direction winds toward or away from the center warm cold rising sinking clouds no clouds counter clockwise clockwise toward away

H L Sea Breeze (daytime) On the diagrams below, label which one represents a land breeze and which represents a sea breeze. Correctly label on each diagram where the high and low pressure areas would be found. H L Warm air Cool air Sea Breeze (daytime)

Land Breeze (night time) On the diagrams below, label which one represents a land breeze and which represents a sea breeze. Correctly label on each diagram where the high and low pressure areas would be found. Warm air H L Cool air Land Breeze (night time)