Don Puttock1 Tephigrams for Dummies An introduction NEXT

Don Puttock2 Introduction to Tephigrams Te phi gram “T” is the symbol used for Temperature “Phi” φ is the symbol used for pressure “gram” means graph (Invented by Napier Shaw in 1915) NEXT

Don Puttock3 Introduction to Tephigrams Pressure Temperature NEXT Temperature normally reduces with height. But not always NEXT

Don Puttock4 Introduction to Tephigrams Pressure Temperature Lower pressure Higher Pressure NEXT Air PressureREDUCESwith altitude NEXT

Don Puttock5 Introduction to Tephigrams Pressure Temperature Higher pressure Lower pressure ALTITUDE NEXT

Don Puttock6 Introduction to Tephigrams Bronze C question The surface temperature is 20°C, The Environmental Lapse Rate (ELR) is 2°C/1000ft. Trigger temperature is 24°C. The Dry Adiabatic Lapse Rate (DALR) is 3°/1000ft. How High will the thermals go? NEXT

Don Puttock7 Introduction to Tephigrams ENVIRONMENTAL LAPSE RATE 2°C/1000ft 1000ft 4000ft 3000ft 2000ft 5000ft 6000ft 7000ft 20°C10°C ALTITUDE But this is idealised---In reality the ELR is never a steady reduction like this TEMPERATURE NEXT

Don Puttock8 Introduction to Tephigrams ACTUAL or FORECAST SOUNDING 1000ft 4000ft 3000ft 2000ft 5000ft 6000ft 7000ft 20°C10°C It is far more usual to see it like this. OR THIS NEXT

Don Puttock9 Introduction to Tephigrams Adiabatic Heating and Cooling of a parcel of air As air expands it also cools As air is compressed it gets warmer cooler NEXT Warmer NEXT

Don Puttock10 Introduction to Tephigrams Air pressure decreases with Altitude If a parcel rises, it expands in the lower pressure above It cools adiabatically NEXT

Don Puttock11 Introduction to Tephigrams In this context, if air has not cooled to its Dew point, it is considered to be dry. The Dry Adiabatic Lapse Rate (DALR) is 3°C/1000ft Air below its Dew Point temperature is saturated. The Saturated Adiabatic Lapse rate (SALR) is approximately 1.5°C/1000ft. NEXT

Don Puttock12 Introduction to Tephigrams 1000ft 4000ft 3000ft 2000ft 5000ft 6000ft 7000ft 20°C10°C DALR≈ 3°/1000ft SALR≈ 1.5°C/1000ft When shown on our graph these lines look like this NEXT

Don Puttock13 Introduction to Tephigrams Remember our question? The surface temperature is 20°C, The Environmental Lapse Rate (ELR) is 2°C/1000ft. Trigger temperature is 24°C. The Dry Adiabatic Lapse Rate (DALR) is 3°/1000ft. How High will the thermals go? NEXT

Don Puttock14 Introduction to Tephigrams 1000ft 4000ft 3000ft 2000ft 5000ft 6000ft 7000ft Surface temperature is20°C The environmental Lapse rate is 2°C/1000ft Environmental air temp 18°C 16°C 14°C 12°C 10°C 8°C 6°C The Sun heats the ground Local Hotspot Warms to Trigger Temp 24°C The local surface warms the air NEXT

Don Puttock15 24°C Introduction to Tephigrams 1000ft 4000ft 3000ft 2000ft 5000ft 6000ft 7000ft 20°C Environmental air temp 16°C 18C 12°C 10°C 8°C 6°C 21°C 18°C 12°C The packet of air stopped rising because it is the same temperature as the environment. The answer to the Bronze C question is 4000ft BUT What if the dew point happened to be 15°C ? The parcel of air is cooling at the DALR, 3°C/1000ft Well Cloud would form from 3000ft 14°C15°C NEXT

Don Puttock16 24°C Introduction to Tephigrams 1000ft 4000ft 3000ft 2000ft 5000ft 6000ft 7000ft 20°C Environmental air temp 16°C 18C 12°C 10°C 8°C 6°C 21°C 18°C 12°C Well Cloud would form from 3000ft 14°C15°C Dewpoint Temp The dewpoint of the air near the surface is (say)15°C As it rises and cools, it might reach its dewpoint If it does, Cloud will form Cloudbase NEXT

Don Puttock17 24°C Introduction to Tephigrams 1000ft 4000ft 3000ft 2000ft 5000ft 6000ft 7000ft 20°C Environmental air temp 16°C 18C 12°C 10°C 8°C 6°C 21°C 18°C SO if the dew point happened to be 15°C The parcel of air is cooling at the DALR, 3°C/1000ft 14°C15°C 12°C 9°C 10.5°C 13.5°C Once saturated, the parcel cools at the SALR The air has now become unstable NEXT

Don Puttock18 Introduction to Tephigrams 1000ft 4000ft 3000ft 2000ft 5000ft 6000ft 7000ft 20°C10°C DALR≈ 3°/1000ft SALR≈ 1.5°C/1000ft Remember this? If the slope of the ELR falls here The airmass isUnstable Conditionally Unstable Stable NEXT

Don Puttock19 Introduction to Tephigrams 1000ft 4000ft 3000ft 2000ft 5000ft 6000ft 7000ft 20°C10°C DALR≈ 3°/1000ft SALR≈ 1.5°C/1000ft Unstable Conditionally Unstable Stable UDCSS =Urban District Council Shovels Snow NEXT

Don Puttock20 NEXT Location, N 52.00° W 2.00° Valid for Date 30 th January 2008 Prediction 0 hours ahead The minus figure indicates West of the prime meridian Introduction to Tephigrams Valid time 12.00hrs Zulu NEXT

Don Puttock21 Introduction to Tephigrams A forecast tephigram. The National Oceanic and Atmospheric Administration (NOAA) Pressures not Altitudes About 30,000ft About sea level About 10,000ft NEXT

Don Puttock22 Introduction to Tephigrams About 30,000ft About sea level About 10,000ft Temperatures, lines skewed at 45° NEXT

Don Puttock23 Introduction to Tephigrams An aid to working out the temperature -6°C NEXT 2°C temperature divisions

Don Puttock24 NEXT Introduction to Tephigrams Wind strength and direction Northwest 35 knots Northwest 60 knots

Don Puttock25 Introduction to Tephigrams NEXT Dry Adiabatic Lapse lines Approx 3°C/1000ft For your convenience Saturated Adiabatic lapse lines Approx 1.6°C/ 1000ft

Don Puttock26 NEXT Moisture content lines Introduction to Tephigrams The amount water the air can hold at that temperature in grammes per Kg

Don Puttock27 Introduction to Tephigrams NEXT So far we have only described the graph paper The two traces on it are Red line is the predicted temperature as we climb through the atmosphere. The Green line is the dew point

Don Puttock28 Introduction to Tephigrams NEXT