|Primary outflows||River Earn|
|Basin countries||United Kingdom|
|Max. length||10.5 km|
|Max. width||1.2 km|
|Max. depth||87 m|
|Settlements||Lochearnhead St Fillans|
Loch Earn (Scottish Gaelic, Loch Eire/Loch Éireann) is a freshwater loch in the central highlands of Scotland, in the districts of Perth and Kinross and Stirling. The name is thought to mean "Loch of Ireland", and it has been suggested that this might derive from the time when the Gaels were expanding their kingdom of Dál Riata eastwards into Pictland. It can be located on Satnav from postcodes including PH6 2NL.
It is a long narrow loch, 17 km west of Crieff and is approximately 10.5 km long, 1.2 km at its widest point (56.38N, 4.22W) and at its deepest point (approximately halfway along) about 87 m. Lochearnhead village is situated at the western end of the loch and St. Fillans village at the eastern end. From here, the River Earn flows eastwards from the loch, through Strathearn, and eventually joins the Firth of Tay some 75 km away. Lochearnhead is the centre for the water sports activities on the loch; water skiing, canoeing and sailing. The loch is also stocked regularly with brown and rainbow trout and fishing, by permit, is possible from the shore and by boat.
To the south of the loch lies Ben Vorlich, a steep sided pyramid shaped peak. At 985m, this is a popular climb and the views from the top are spectacular. Just east of Lochearnhead, on the south side of the loch, is Edinample Castle, built by 'Black' Duncan Campbell of Glenorchy in 1584. Further east is Ardvorlich House, home to the Stewarts of Ardvorlich from 1580 (rebuilt in 1790).
Loch Earn is unusual in that it has its own apparent 'tidal system', or seiche, caused by the action of the prevailing wind blowing along the loch. This wind pressure on the surface causes the water level to build up at one end of the loch. As with all damped mechanical systems, applied pressure can result in an oscillation, and the water will return to the opposite end of the loch over time. In the case of Loch Earn, this has a period of 16 hours and the effect can be measured, but is difficult to observe. The resulting currents can create complex turbulence patterns, as higher layers of warmer waters mix with the lower lying colder waters of the loch.
- McNaughton, D,(1988) “The History of Upper Strathearn”, Jamieson & Munro.
- Murray, J, 1906. An investigation of the seiches of Loch Earn by the Scottish Lake Survey, Part 2, Preliminary limnographic investigations on Loch Earn. Trans. Roy. Soc. Edinb., 45, 387-396.
- MacManus, J. and R. W Duck, Internal seiches and subaqueous landforms in lacustrine cohesive sediments, Nature, 334, 511-513, 1988
- David B. McNaughton, The History of Upper Strathearn, Jamieson & Munro (1988)