Learn Hardcore Turkish: Yıldırım tehlikeli, ormanda yürüyüş yapmak yerine evde kalalım. - Lightning is dangerous; instead of walking in the forest, let’s stay at home.

Turkish nominal sentences don’t need an explicit “to be” in the simple present. Yıldırım tehlikeli literally “Lightning dangerous” = “Lightning is dangerous.” You can add the -dir ending for a more formal/gnomic tone: Yıldırım tehlikelidir.

What’s the difference between yıldırım and şimşek?

yıldırım: a lightning strike (especially one that hits the ground). Collocation: yıldırım düşmek (lightning strikes).
şimşek: the flash of lightning/lightning in the sky. Collocation: şimşek çakmak (lightning flashes). In a safety context, yıldırım is the natural choice.

How does yerine work in this sentence?

X yerine Y means “instead of X, (do) Y.” Here: ormanda yürüyüş yapmak yerine evde kalalım = “Instead of going for a walk in the forest, let’s stay at home.” With pronouns you’ll see genitive: onun yerine (instead of him/her/it).

Could I say ormanda yürümek yerine instead of ormanda yürüyüş yapmak yerine?

Yes. Ormanda yürümek yerine is perfectly natural. Nuance:

yürümek = to walk (the action)
yürüyüş yapmak = to go for a walk/a hike (set phrase, sounds more like a planned recreational walk) Both work here.

Why ormanda and evde? What is that -da/-de ending?

That’s the locative case, “in/on/at.” It follows vowel harmony and voicing:

orman (forest) → ormanda (in the forest)
ev (home/house) → evde (at home) Use -da/-de after voiced finals; -ta/-te after voiceless finals.

Why evde kalalım and not eve kalalım?

Kalmak (to stay) takes the locative: evde (at home). The dative eve means “to home” and is used with motion verbs (e.g., eve gidelim = let’s go home).

What does yürüyüş yapmak literally mean? Is that construction common?

Literally “to do a walk,” and yes, noun + yapmak is very common:

alışveriş yapmak (to do shopping)
spor yapmak (to do sports/exercise)
araştırma yapmak (to do research)

Why isn’t it yürüyüşü yapmak (with -ı)?

In Turkish, an indefinite direct object usually has no accusative ending. Yürüyüş yapmak = “do a/ some walk(ing).” The accusative (-ı/-i/-u/-ü) marks a specific/definite object: O yürüyüşü yapmayalım (let’s not do that particular walk).

Is the comma natural here? Could I use a connector like çünkü or bu yüzden?

The comma is fine in a casual, paratactic style. Alternatives:

Yıldırım tehlikeli olduğu için evde kalalım. (Since lightning is dangerous…)
Yıldırım tehlikeli, bu yüzden evde kalalım. (…therefore…) If you use çünkü (because), it typically introduces the reason after the main clause: Evde kalalım, çünkü yıldırım tehlikeli.

Can I move parts around? For example, put evde earlier?

Yes, Turkish word order is flexible for focus. These are natural:

Yıldırım tehlikeli; evde kalalım, ormanda yürüyüş yapmak yerine.
Yıldırım tehlikeli, evde kalalım. Ormanda yürüyüş yapmak yerine. (more speech-like) Keeping evde right before kalalım is the default.

Any pronunciation tips for yıldırım and yürüyüş?

ı (dotless i) in yıldırım is a back, unrounded vowel [ɯ], not like English i.
ü in yürüyüş is a front rounded vowel [y], like German ü or French u.
ş = “sh.” So roughly: “yɯl-dɯ-rɯm” and “yü-rü-yüsh.”

How would I say “Instead of staying at home, let’s go for a walk in the forest”?

Evde kalmak yerine ormanda yürüyüş yapalım. (Or: …ormanda yürüyelim.)

Any softer or more polite ways than kalalım?

Evde kalsak mı? (Shall we stay at home?)
Evde kalsak iyi olur. (It would be good if we stayed at home.)
Bence evde kalalım. (I think we should stay at home.)
Evde kalmayı öneriyorum. (I suggest staying at home.)

Is da/de here the locative or the “also” particle? How do I tell?

In ormanda/evde, it’s the locative suffix, written attached to the noun. The clitic meaning “also/too,” da/de, is written separately and moves for emphasis: Orman da tehlikeli (The forest is dangerous too).