[b]the latitude of Brussels is 51° N.[/b][br][list][*][b]axial tilt = -23,5°[/b]: On the 21th of june the north pole is tilted towards the sun. In Brussel and the rest of the northern hemisphere days are longer than the nights. The angle of incidence of the sunrays is maximal.[br][/*][*][b][b]axial tilt[/b] = 0°[/b]: On the 21th of march and the 21th of september the length of day and night is equal. The angle of incidence of the sunrays is lower than on the 21th of june.[/*][*][b][b]axial tilt[/b] = 23,5°[/b]: On the 21th of december the north pole is tilted away from the sun. In Brussel and the rest of the northern hemisphere nights are longer than the days. The sun in the sky is at its lowest point.[br][/*][/list]

Click on the checkbox [i]polar zones and tropics[/i].[br][b]polar zones[/b][br][list][*][b]axial tilt = -23,5°[/b]: On the 21th of june the entire zone above the north pole circle is in the day zone. There's no sunset. On the contrary on the south pole there's no sunrise. Nigh is 24 uur long.[/*][*][b][b]axial tilt[/b] = 23,5°[/b]: On the 21the december it's the opposite situation. On the north pole it's night for 24 hours, on the south pole we have a polar day for 24 hours.[/*][*][b]North- and south pole circles[/b] mark the zones were the phenomenon of a polar day and polar night of 24 hours occurs.[/*][/list][b]tropics[/b][br][list][*][b][b]axial tilt[/b] = -23,5°[/b]: The sun is perpendicular to a place with latitude of 23,5° N (= [b]tropic of cancer[/b])[/*][*][b][b]axial tilt[/b] = 0°[/b]: The sun is perpendicular to the equator.[br][/*][*][b][b]axial tilt[/b] = 23,5°[/b]: The sun is perpendicular to a place with latitude of 23,5° S (= [b]tropic of capricorn[/b]).[/*][*]The two [b]tropics[/b] mark the zone where the sun can stand perpendicular in the sky.[/*][/list]

[table][tr][td]64°[/td][td]Reykjavik [br][/td][td]42°[/td][td]Rome[/td][td]35.5°[/td][td]Tokyo[/td][td]14°[/td][td]Bangkok[/td][/tr][tr][td]60°[/td][td]Helsinki[/td][td]40.5°[/td][td]Madrid[/td][td]34°[/td][td]Los Angeles[/td][td]12.5°[/td][td]Bamako[/td][/tr][tr][td]55.5°[/td][td]Moskou[/td][td]41°[/td][td]New York [/td][td]30°[/td][td]Cairo[/td][td]4.5°[/td][td]Bogota[/td][/tr][tr][td]49°[/td][td]Paris[/td][td]40°[/td][td]Bejing[/td][td]28.5[/td][td]Delhi[/td][td]3°[/td][td]Kuala Lumpur[/td][/tr][tr][td]48°[/td][td]Linz[/td][td]38°[/td][td]Athens[/td][td]19.5[/td][td]Mexico City [/td][td]0.5°[/td][td]Kampala[/td][/tr][/table]